Mémoire (M.Ress.Renouv.)-- Université du Québec à Chicoutimi, 1993. / Bibliogr.: f. 145-153. Document électronique également accessible en format PDF. CaQCU

Mémoire (M.Ress.Renouv.)-- Université du Québec à Chicoutimi, 1993. / Document électronique également accessible en format PDF. CaQCU

Mémoire (M.Ress.Renouv.)--Université du Québec à Chicoutimi, 2001. / Document électronique également accessible en format PDF. CaQCU

Thèse (M.Ress.Renouv.) -- Université du Québec à Chicoutimi, 2004. / Bibliogr.: f. [72]-78. Document électronique également accessible en format PDF. CaQCU

Thèse (M.Ress.Renouv..) -- Université du Québec à Chicoutimi, 2006. / Bibliogr.: f. 40-52. Document électronique également accessible en format PDF. CaQCU

Inaug.-Diss.--Sofia. / Bibliography: p. [35]-38.

Η αιμοποιητική φωλαιά (hematopoietic stem cell niche) περιέχει οστεοβλάστες, οι οποίοι ρυθμίζουν τη φυσιολογική αιμοποίηση. Ωστόσο, λίγα στοιχεία είναι γνωστά, έως τώρα, για το ρόλο των οστεοβλαστών στη διαδικασία της αιμοποίησης σε ασθενείς με Μυελοδυσπλαστικό Σύνδρομο (ΜΔΣ). Το ΜΔΣ, αποτελεί μια ετερογενή ομάδα κλωνικών αιματολογικών διαταραχών, με αυξημένο κίνδυνο εκτροπής προς Οξεία Μυελογενή Λευχαιμία (ΟΜΛ). Μελέτες σε ex-vivo συστήματα καλλιεργειών (co-cultures) περιγράφουν την επίδραση των μεσεγχυματικών κυττάρων (“feeder cells”) στο δυναμικό πολλαπλασιασμού, στη μεταναστευτική ικανότητα, καθώς και στη διατήρηση (stemness) των αρχέγονων αιμοποιητικών κυττάρων (HSCs) φυσιολογικών δοτών. Η μελέτη αυτή στοχεύει στη διερεύνηση των βιολογικών χαρακτηριστικών των οστεοβλαστών από ασθενείς με ΜΔΣ καθώς και τις αλληλεπιδράσεις φυσιολογικών HSCs και οστεοβλαστών ασθενών με ΜΔΣ. Για το σκοπό αυτό δημιουργήθηκε ένα σύστημα δισδιάστατης καλλιέργειας (2-D culture system) χρησιμοποιώντας οστεοβλάστες που παρήχθησαν από μεσεγχυματικά κύτταρα μυελού των οστών (human marrow mesenchymal stem cells-MSCs). Τα MSCs απομονώθηκαν από το μυελό των οστών ασθενών με ΜΔΣ και υγιών δοτών και καλλιεργήθηκαν σε κατάλληλο θρεπτικό μέσο. Ακολούθησε επαγωγή της διαφοροποίησης των MSCs, μετά από συνεχόμενες καλλιέργειες σε οστεοβλάστες. Στη μελέτη χρησιμοποιήθηκαν 13 δείγματα μυελού των οστών από ασθενείς με ΜΔΣ (6 RA, 3 RAEBI, 2 RAEBII, 1 5q- και 1 υποπλαστικό MDS) και 8 δείγματα μυελού φυσιολογικών μαρτύρων όμοιας ηλικίας. Για τη μελέτη της επίδρασης των οστεοβλαστών από ασθενείς με ΜΔΣ στην αιμοποίηση χρησιμοποιήθηκαν φυσιολογικά HSCs από κινητοποιημένο περιφερικό αίμα υγιών δοτών (mPB, n=4), τα οποία τοποθετήθηκαν πάνω στους ήδη εγκατεστημένους οστεοβλάστες (osteoblast confluent monolayer cultures). Τα MSCs και οι οστεοβλάστες που αναπτύχθηκαν ελέγχθηκαν μορφολογικά και ανοσοφαινοτυπικά, με τη χρήση μικροσκοπίας και κυτταρομετρίας ροής αντίστοιχα. Μονοπύρηνα κύτταρα από δείγματα κινητοποιημένου περιφερικού αίματος υγιών δοτών τοποθετήθηκαν στο δισδιάστατο καλλιεργητικό σύστημα, σε καλλιεργητικό υλικό αιμοποιητικών κυττάρων, χωρίς την εξωγενή προσθήκη κυτταροκινών. Με τη χρήση κυτταρομετρίας ροής ελέγχθηκε η έκφραση των μορίων που σχετίζονται με την προσκόλληση των αιμοποιητικών κυττάρων στην αιμοποιητική φωλαιά καθώς και την εγκατάσταση και διατήρησή τους σε αυτή. Ο έλεγχος έγινε στις 36 ώρες και τις 7 ημέρες συγκαλλιέργειας και αφορούσε τα μόρια CXCR4, το οποίο ρυθμίζει την άμεση πρόσδεση των HSCs στην φωλαιά κατά τη διαδικασία του “homing”, CD49d (Very Late Antigen-4- VLA4) και CD49e (Very Late Antigen-5- VLA5), τα οποία παρέχουν σήματα επιβίωσης ή προάγουν την ενεργοποίηση μιας φάσης ηρεμίας (quiescence) στα HSCs μετά την είσοδο τους στη φωλαιά (localization). Η έκφραση των μορίων αυτών μελετήθηκε στους υποπληθυσμούς των CD34+, CD34+/CD38+ και CD34+/CD38- κυττάρων. Παράλληλα εκτιμήθηκε το ποσοστό (συχνότητα) των CD34+ αιμοποιητικών κυττάρων καθώς επίσης και η προσκόλλησή τους στους οστεοβλάστες. Μετά τη συγκαλλιέργεια, οι οστεοβλάστες που προήλθαν από υγιείς δότες προκάλεσαν τον πολλαπλασιασμό των CD34+ κυττάρων των φυσιολογικών αιμοποιητικών κυττάρων που τοποθετήθηκαν πάνω στο εγκατεστημένο στρώμα των οστεοβλαστών (3-fold και 9-fold αύξηση στις 36ώρες και τις 7ημ., αντίστοιχα). Αύξηση επίσης, παρατηρήθηκε (2 fold αύξηση) στα CD34+ κύτταρα στις συγκαλλιέργειες των 36h, φυσιολογικών HSCs με οστεοβλάστες που παρήχθησαν από ασθενείς με ΜΔΣ, ενώ καμία διαφορά δεν παρατηρήθηκε μεταξύ των διαφορετικών υποτύπων ΜΔΣ. Στις 7 ημέρες συγκαλλιέργειας από την άλλη, δεν 12 παρατηρήθηκε καμία διαφορά στη συχνότητα εμφάνισης ενός πιο άωρου φαινοτύπου των φυσιολογικών HSCs που αναπτύχθηκαν σε οστεοβλάστες από ασθενείς με χαμηλού κινδύνου ΜΔΣ (low risk MDS). Αντιθέτως, τα CD34+ κύτταρα αυξήθηκαν κατά πολύ (16- fold αύξηση), όταν φυσιολογικά HSCs, τοποθετήθηκαν σε οστεοβλάστες ασθενών με υψηλού κινδύνου ΜΔΣ (high risk MDS). Επιπλέον, παρατηρήθηκε αύξηση της έκφρασης των μορίων CXCR4, CD49d και CD49e στα CD34+ κύτταρα μετά από συγκαλλιέργεια φυσιολογικών HSCs και οστεοβλαστών από υγιείς δότες, συγκριτικά με τα επίπεδα έκφρασης των μορίων αυτών πριν την τοποθέτηση τους στο σύστημα συγκαλλιέργειας. Η αύξηση της έκφρασης του μορίου CXCR4 ήταν λιγότερο εμφανής στην περίπτωση συγκαλλιέργειας των φυσιολογικών HSCs με οστεοβλάστες από ασθενείς με ΜΔΣ, όπου η μεγαλύτερη διαφορά παρατηρήθηκε στο σύστημα που περιείχε τους οστεοβλάστες από ασθενείς χαμηλού κινδύνου ΜΔΣ (3- και 1,7- fold αύξηση στις 7ημέρες καλλιέργειας με οστεοβλάστες από υγιείς δότες και χαμηλού κινδύνου ΜΔΣ ασθενείς, αντίστοιχα). Το πρότυπο έκφρασης των μορίων CD49d και CD49e ήταν όμοιο στα κύτταρα που τοποθετήθηκαν τόσο σε οστεοβλάστες προερχόμενους από υγιείς δότες, όσο και οστεοβλάστες από ΜΔΣ ασθενείς. Ο φαινότυπος, τόσο όσον αφορά τα μορφολογικά όσο και τα ανοσοφαινοτυπικά χαρακτηριστικά, των MSCs ήταν ίδιος και στις δυο ομάδες μελέτης, ενώ η διαφοροποίηση των MSCs προς οστεοβλάστες ήταν όμοια τόσο στα MSCs που προήλθαν από φυσιολογικούς δότες όσο και σε αυτά που προήλθαν από ασθενείς με ΜΔΣ, δείχνοντας παρόμοια έκφραση των ειδικών οστεοβλαστικών πρωτεϊνών αλλά και της διαδικασίας της ενασβεστοποίησης. Σύμφωνα με τα αποτελέσματα που λάβαμε, οι οστεοβλάστες από υγιείς δότες προώθησαν την αύξηση του ποσοστού των προγονικών αιμοποιητικών κυττάρων και οδήγησαν στην επαγωγή της έκφρασης του μορίου CXCR4, ενός πολύ σημαντικού μορίου για τη μετανάστευση, την εγκατάσταση αλλά και την ανάπτυξη. Ωστόσο, η διαφορετική δραστηριότητα, τόσο όσον αφορά το ποσοστό των CD34+ όσο και την έκφραση του μορίου CXCR4, όταν τα φυσιολογικά αιμοποιητικά κύτταρα συγκαλλιεργήθαν με οστεοβλάστες που προήλθαν από ασθενείς με ΜΔΣ, οδηγεί στην υπόθεση ότι υπάρχει μεταβολή στη λειτουργία των οστεοβλαστών, οπότε προβλέπεται και μια επακόλουθη αλλαγή στη ρύθμιση της εγκατάστασης των HSC στην αιμοποιητική φωλαιά, στους ασθενείς με ΜΔΣ. / The hematopoietic stem cell niche contains osteoblasts that regulate normal hematopoiesis. However, little is known about the role of osteoblasts in MDS hematopoiesis so far. Myelodysplastic syndrome comprises a heterogeneous group of clonal stem cell disorders with dismal prognosis and difficulty in their therapeutic approach, which is characterized by ineffective hematopoiesis. It appears with dysplastic hematopoietic cells, peripheral blood cytopenias and high risk of evolution to acute myeloid leukemia (AML). Data derived from ex vivo co-culture systems using mesenchymal stromal cells as a feeder cell layer suggest that cell-cell contact has a significant impact on the expansion, migratory potential and “stemness” of hematopoietic stem cells. In this study, we investigated the biological characteristics of osteoblasts from MDS patients and the interactions between these cells and normal hematopoietic stem cells (HSCs). Osteoblasts were differentiated from marrow MSCs from 13 MDS patients (6 RA, 3 RAEBI, 2 RAEBII, 1 5q- and 1 hypoplastic MDS) and 8 age-matched healthy individuals. To study the effect of MDS osteoblasts on hematopoiesis, normal HSCs from mobilized peripheral blood from healthy individuals (n=4) were seeded onto osteoblast confluent monolayer cultures using a culture medium appropriate for the culture of HSCs, without the exogenous addition of cytokines. We studied the morphology and immunophenotype of MSCs and osteoblasts by microscopy and flow cytometric analysis, respectively. Cytometric analyses of homing associated molecules were performed 36h and 7d later. These molecules are CXCR4, which regulates the direct adhesion of HSCs to the bone marrow niche during “homing”, CD49d (Very Late Antigen-4- VLA4) and CD49e (Very Late Antigen-5- VLA5), which produce survival signals or promote the maintenance of a quiescent state for HSCs after entering the stem cell niche (localization). We investigated the expression of these molecules in CD34+, CD34+/CD38+ and CD34+/CD38- cell populations. Furthermore we studied the frequency of CD34+ hematopoietic cells and also their ability to adhere osteoblasts.Osteoblasts from healthy individuals increased the frequency of CD34+ cells by 3- and 9-fold increase in normal hematopoietic cells after 36h and 7d co-cultures respectively. A 2-fold increase was also seen in CD34+ cells when normal HSCs grown on MDS-osteoblasts for 36h and no difference was seen between the MDS subtypes. When the culture period was extended to 7d, there was no change in the frequency of immature phenotype of normal HSCs in osteoblast cultures from low-risk MDS patients. In contrast, CD34+ cells increased several fold (16-fold increase) when normal HSCs were cultured on high-risk MDS 14 osteoblasts, twice the values obtained in osteoblast co-cultures from healthy individuals and low risk patients. The expression of adhesion molecules CXCR4, CD49d and CD49e on CD34+ cells from normal HSCs was increased in co-cultures with osteoblasts from healthy individuals compared to the values obtained before culture (3-fold increase at 7d). The increase in CXCR4 expression was less pronounced in the presence of osteoblasts from MDS patients with the largest difference being found in low-risk MDS patients (1,7-fold increase at 7d). The expression pattern of CD49d and CD49e was identical between cells grown on MDS- and normal- osteoblast co-cultures.The morphological and immunophenotypical analysis of MSCs show the same results for the two study groups, while the differentiation of MSCs to osteoblasts was similar for both healthy individuals and MDS patients, after having similar expression of bone specific proteins and mineralization activity. According to our data, osteoblasts from healthy individuals promoted the expansion of immature hematopoietic progenitors and induced the cell surface expression of CXCR4, an important molecule in HSCs homing, retention and development. However, the different expression of CXCR4 and the change in frequency of CD34+ cells that were detected when normal HSCs co-operated with MDS-osteoblasts, suggests alteration in osteoblast function and the subsequent regulation of the HSC residency in the niche in MDS patients compared with healthy individuals.

Thesis (MSc)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: A total of 125 trees covering a range of tree diameters were selected from a progeny trial of open pollinated progenies of Pinus patuia for studies on trait assessments and evaluation for branching characteristics. The trees comprised 25 families with each family having five trees. The trial was 36 months old and was located in a relatively high yielding site in Block B at Usutu in Swaziland. The height, diameter, the number of branches and the number of whorls of each tree were recorded. In addition to these objective assessments on individual trees, trees were given scores for branch size, branch angle, stem straightness and crown coarseness. For the detailed branch evaluation study, trees were marked at 20% and 50% of the total tree height and the section between this range was used. On this section the internode length, the internode diameter, the branch diameter and the branch angle were measured. It was observed that the objective assessments correlated strongly with the scoring (subjective) and it was further recommended that a closer look is needed to consider the prospects of employing subjective assessments as a means of reducing costs incurred during objective trait assessments. The branch sampling study revealed that there were prospects of assessing fewer branches on a tree as opposed to assessing all the branches, which could be a major contributor to the high costs in tree breeding. All three methods used to explore this prospect showed some reasonable agreement with each other in this regard. The best sample is to measure all branches in whorl one and two above 20% tree height followed by sampling four branches, two from the first whorl and two from the second whorl. There is a slight difference in these two samples as determined by the coefficents of determination. The study recommends that four branches can be used in the assessment of the branch angle and the branch diameter on the trees when one considered the cost elements. / AFRIKAANSE OPSOMMING: In 'n ondersoek na die evaluering van tak-eienskappe van Pinus patuIa is 125 bome in 'n oop-bestuifde nageslags-proef geselekteer. Hierdie bome is gekies met groottes wat strek oor 'n wye verskeidenheid van borshoogtedeursnee. Die ondersoek het 25 families ingesluit met elke familie wat uit 5 bome bestaan. Die proef is 36 maande oud en is gevestig in'n hoë produksiearea van Blok B, Usutu, in Swaziland. Die hoogte, borshoogtedeurnee, aantal takke en die hoeveelheid takkranse is gemeet en bepaal by elk van die 125 bome. Verder is punte toegeken vir takgrootte, takhoek, graad van stamkromming en kroon grofheid. In die gedetailleerde tak-evaluasie is slegs die stamseksie tussen 200!o en 50% van die totale boomhoogte gebruik. Op hierdie seksie van die boomstam is die internodale afstand, die internodale deursnee, die takdeursnee en die tak-hoek gemeet. Uit die gegewens wat versamel is, het dit geblyk dat daar sterk korrelasie tussen die objektiewe evaluasie en die subjektiewe evaluasie (met gebruik van kwalitatiewe eienskappe op 'n tellingbasis) verkry is. Hieruit word aanbeveel dat meer aandag aan subjektiewe evaluasie (as vereenvoudigde evaluasieprosedure) bestee word om kostes te besnoei. Die gedetailleerde tak-evaluasiestudie het aangedui dat die gebruik van slegs 'n paar takke, in teenstelling met al die takke op die boom, voordelig kan wees om verdere kostes van evaluasie te bespaar. Die beste monster is om al die takke in die eerste twee takkranse bo 20% boomhoogte te meet. Daarnaas is die beste monster die eerste twee grootste takke in die eerste en tweede takkranse. Die gebruik van hierdie kleiner monsters vir evaluering het in sekere opsigte nog beter voorspellings gelewer as in die gevalle waar al die takke in die eerste takkrans gebruik is. Die studie b aan dat In betroubare monster van vier takke (twee uit elke takkrans bo 20% boomhoogte) geneem kan word om die boom se takeienskappe te be-oordeel.

Diversos estudos de anatomia vegetal abordaram as variações cambiais frequentemente presentes nos caules de lianas de Sapindaceae, mas trabalhos que se baseiam na análise das raízes ainda são pouco frequentes na literatura. Por essa razão, a presente dissertação procura atender a dois objetivos, assim distribuídos. No primeiro capítulo, foi realizada uma análise comparada macroscópica de raízes e caules de 14 espécies lianescentes de cinco gêneros de Sapindaceae para verificar se os dois órgãos apresentam os mesmos tipos de variações cambiais e se a anatomia do xilema secundário é semelhante. No segundo capítulo, analisaram-se detalhadamente, em termos macro e microscópicos, as raízes da espécie Serjania caracasana para observar anatomicamente a configuração do xilema e floema secundários e as variações cambiais, além de verificar se existem conexões entre os cilindros vasculares periféricos neoformados e o cilindro central. Os resultados, em síntese, evidenciaram que: I. O principal tipo de variação cambial caulinar está ausente nas raízes; II. O xilema e o floema secundário das raízes amostradas são macro e microscopicamente similares aos dos caules; III. Xilema interrompido por cunhas de floema e neoformações de cilindros vasculares periféricos foram observados em raízes e caules em estágio avançado de desenvolvimento; IV. Conexões vasculares entre os cilindros neoformados e o cilindro vascular original aparecem em diversos pontos das raízes de Serjania caracasana. / A number of studies in plant anatomy have explored the cambial variants present in the stems of Sapindaceae lianas, while works based on root analysis are still meagre in the literature. Therefore, the present dissertation aims to fulfil two objectives, distributed as follow. In the first chapter, a macroscopic comparative analysis of stems and roots of 14 lianescent species from five genera of Sapindaceae was carried to check whether the two organs presented the same types of cambial variants and whether the secondary xylem anatomy was similar. In the second chapter, roots of Serjania caracasana are analysed in detail under macro and microscopic perspectives, in order to anatomically explore the secondary xylem and phloem configuration and the cambial variants, in addition to verify whether there are connections between the neoformed peripheral vascular cylinders and the central vascular cylinder. The results, in synthesis, evidence that: I. The main type of cambial variant present in the stem is absent in the roots; II. The secondary xylem and phloem of the roots are macro and microscopically similar to those of the stem; III. Xylem furrowed by phloem wedges and neoformations of peripheral vascular cylinders was encountered in roots and stems in mature stages of development; IV. Vascular connections between the neoformed vascular cylinders and the central vascular cylinder appear in many parts of the roots of Serjania caracasana.

O presente estudo teve por objetivo a avaliação do efeito de estádios de maturidade de cultivares de milho (Zea mays L.) para produção de silagem sobre os parâmetros agronômicos e qualitativos da planta e das frações que a compõem. Foram avaliados seis híbridos de milho para silagem, colhidos em oito estádios de maturidade, em dois anos agrícolas, safra de 2002 e 2003. As plantas atingiram o teor de matéria seca (MS) recomendado para ensilagem (32 a 35% MS) entre 92 e 112 dias após a semeadura (DAS). O híbrido CO 32 apresentou os maiores (P<0,05) teores de MS da planta e do colmo, e as menores (P<0,05) produções MS do colmo ao longo do período de avaliação, enquanto o híbrido P 3041 obteve os menores (P<0,05) teores de MS da planta e do colmo. Os híbridos DKB 333B e AG 1051, de ciclo normal, apresentaram as maiores (P<0,05) produções de colmo no 1&#186;, 3&#186;, 4&#186;, 5&#186; e 8&#186; corte. O avanço da maturidade resultou em aumentos (P<0,05) no teor de MS da planta (de 14,5 para 46%) e do colmo (de 16,9 para 28%), produção de MS da planta (de 9,6 para 20,9 t MS/ha) e produção de grãos (de 0 para 9,3 t MS/ha). Aumentos (P<0,05) nos teores de MS das frações folha (de 23,2 para 48,8%), sabugo (de 10,0 para 55,5%) e grãos (de 50,4 para 70,9%) também foram observados ao longo do tempo. Além disso, observou-se aumentos (P<0,05) nas porcentagens de sabugo (de 1,6 para 9,2%) e grãos (de 0 para 43,4%), e redução (P<0,05) na porcentagem de colmo (de 63,4 para 29,5%) e folhas (de 27,5 para 10,8%). Com o avanço da maturidade foram observados aumentos (P<0,05) nos teores médios de amido da planta (1,8 a 26,1%) e do grão (60,2 a 91,9%); e na produção de matéria seca digestível (PMSD) da planta (7,2 a 16,3 t/ha) e do grão (3,3 a 8,9 t/ha). Em contrapartida, verificou-se redução (P<0,05) nos teores de fibra em detergente neutro (FDN) da planta (71,9 para 52,8%); FDN digestível da planta (64,7 para 54,4%) e do colmo (55,2 para 39,6%); proteína bruta (PB) da planta (12,5 para 7,0%) e do colmo (7,0 para 4,2%); e na digestibilidade verdadeira in vitro da MS (DVIVMS) do colmo (66 para 53,7%) e do grão (99,1 para 96,4%). No ponto de ensilagem, os híbridos P 3041, AG 1051 e Z 8550 foram os materiais que apresentaram as características mais desejáveis na confecção de silagem de qualidade. Para a fração colmo, o híbrido Z 8550 apresentou os menores (P<0,05) teores de PB e FDN, e os maiores (P<0,05) teores de FDN digestível, DVIVMS e PMSD. Os híbridos P 3041, DKB 333B e AG 1051, de endosperma duro, apresentaram juntamente com o híbrido Z 8550, as maiores (P<0,05) PMSD do colmo. No ponto de ensilagem, o maior (P<0,05) teor de amido do grão foi observado para os híbridos de endosperma duro (P 3041 e DKB 333B), enquanto que a maior (P<0,05) DVIVMS do grão foi verificada para os materiais de endosperma dentado (AG 5011 e AG 1051). A avaliação detalhada da planta, levando em consideração a produtividade, a participação percentual dos seus componentes, além da composição química intrínseca dos mesmos é fundamental para a adequação do processo de ensilagem e êxito dos sistemas de produção. / The objective of this experiment was to evaluate the effect of the maturity stage of corn (Zea mays L.) cultivars for silage production on agronomic and qualitative parameters of plant and its compounds. Six corn silage cultivars were evaluated in eight maturity stages, and two harvesting seasons (2002 and 2003). The plants reached the recommended dry matter (DM) content for silage production (32 to 35% DM) between 92 and 112 days after sowing (DAS). The cultivar CO 32 showed the highest (P<0.05) plant and stem DM content, and the lowest (P<0.05) stem DM production along the evaluation period, while P 3041 cultivar achieved the lowest (P<0,05) plant and stem DM content. The normal maturity cycle cultivars DKB 333B and AG 1051, showed the highest (P<0.05) stem production at 1st, 3rd, 4th, 5th and 8th harvesting age. As maturity advance there were increases (P<0.05) of plant DM content, (from 14.5 to 46%), stem DM content (from 16.9 to 28%), plant DM production (from 9.6 to 20.9 t DM/ha) and grain production (from 0 to 9.3 t DM/ha). Increases (P<0.05) of leaves DM content (from 23.2 to 48.8%), cob DM content (from 10 to 55.5%), and grains DM content (from 50.4 to 70.9%) were observed according to the maturity stage. Furthermore, resulted in increases (P<0.05) in cob percentage (from 1.6 to 9.2%) and grain percentage (from 0 to 43.4%), and decreases (P<0.05) in stem percentage (from 63.4 to 29.5%) and leaves percentage (from 27.5 to 10.8%) as plants matured. Plant maturing resulted in increases in plant (1.8 to 26.1%) and grain (60.2 to 91.9%) starch content, and in the plant (7.2 to 16.3 t/ha) and grain (3.3 to 8.9 t/ha) digestible DM production. However there were verified decreases (P<0.05) in plant (71.9 to 52.8%) neutral detergent fiber (NDF), plant (64.7 to 54.4%) and stem (55.2 to 39.6%) digestible NDF, plant (12.5 to 7.0%) and stem (7.0 to 4.2%) crude protein (CP), and stem (66 to 53.7%) and grain (99.1 to 96.4%) in vitro true dry matter digestibility (IVTDMD) content. At the ensilage moment, P 3041, AG 1051 and Z 8550 cultivars showed the most desirable characteristics for silage production with quality. For the stem fraction, Z 8550 cultivar showed the lowest (P<0.05) CP and NDF content, and the highest values (P<0.05) for stem digestible NDF, IVTDMD, and digestible DM productions. The cultivars P 3041, DKB 333B and AG 1051, with hard endosperm, showed together with Z 8550 cultivar, the highest (P<0.05) stem DDMP. For the grain, it was observed that at the ensilage moment, the highest (P<0.05) starch content was verified for the hard endosperm cultivars (P 3041 and DKB 333B), while the highest (P<0.05) IVTDMD was observed for the soft endosperm cultivars (AG 5011 e AG 1051). Grain DDMP was similar (P>0.05) for the evaluated cultivars.