Thesis (Ph. D. in Cell and Developmental Biology)--Vanderbilt University, Dec. 2009. / Title from title screen. Includes bibliographical references.

Thesis (Ph. D.)--Washington State University, May 2009. / Title from PDF title page (viewed on June 1, 2009). "School of Molecular Biosciences." Includes bibliographical references.

Thesis (Ph.D.)--Kent State University, 2009. / Title from PDF t.p. (viewed May 17, 2010). Advisor: Srinivasan Vijayaraghavan. Keywords: sperm; spermatogenesis; PP1gamma2; PP1gamma1; mice; transgene. Includes bibliographical references (p. 102-123).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1965. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Presented as Thesis (Ph. D.)--University of Wisconsin--Madison, 1925. / Reprinted from Biological bulletin, vol. L, no. 2 (Feb. 1926). Includes bibliographical references (p. 139-140).

Thesis--Leiden. / "Stellingen" inserted. Summary in Dutch. Includes bibliographical references (p. 152-161).

Thesis (Ph. D.)--University of Chicago, 1912. / "Reprinted from the Botanical gazette, Vol. LIV, No. 2, August 1912." "Literature cited": p. 114-118. Also available on the Internet. Also issued online.

Luteinizing hormone (LH), one of the two gonadotropin hormones released from the anterior pituitary gland, binds to its receptor (LHR) in the gonads to stimulate steroid hormone production, in addition to ovulation and gametogenesis. Mutations of the receptors amino acid sequence have the ability to either constitutively activate or inactivate it. All activating mutations result in male-limited precocious puberty. Males with this condition undergo puberty around 4 years of age, and have a premature elevation in testosterone levels and premature skeletal development. In order to understand how chronic ligand-mediated activation of the LHR affects gonadal development and function, a mouse model expressing a yoked hormone-receptor (YHR) complex, engineered by covalently linking the hormone human chorionic gonadotropin to the rat LHR, has been studied. YHR+ males have prepubertally elevated testosterone and decreased gonadotropin levels, smaller testis, and smaller average seminiferous tubule diameters when compared to wild type (WT) animals. In a preliminary breeding study it was shown that YHR+ males were sub-fertile. Based the phenotype exhibited by the YHR+ mice, it was hypothesized that increased levels of testosterone in addition to decreased gonadotropin hormone levels in neonatal and prepubertal mice that results from premature activation of the luteinizing hormone receptor causes spermatogenesis to be impaired. The first objective of this study was to determine if there was a difference in the testicular germ cell and Sertoli cell populations in the WT and YHR+ animals using flow cytometry and systematic Sertoli cell counting, respectively. There was no difference in the Sertoli cell population between YHR+ animals and WT controls, but there were significantly fewer total germ cells in YHR+ animals at 10 days and from 4 weeks through adulthood. The second objective was to calculate the daily sperm production in the testis and epididymis of WT and YHR+ animals in order to determine if there is a further decrease in the total sperm count due to an epididymal dysfunction. Interestingly, there were significantly fewer sperm calculated in the caput/corpus region of the epididymis in YHR+ males at 12 weeks of age, but not in the testis and cauda epididymis. Furthermore, the daily sperm production in WT and YHR+ mice at 16 weeks of age were not significantly different. The final objective was to determine if the decrease in germ cells observed in YHR+ animals is the result of decreased proliferation or an increase in either germ cell or Sertoli cell apoptosis. Quantification of germ cell and Sertoli cell proliferation revealed no significant difference between the WT and YHR+ animals. Similar findings were found after quantification of apoptotic germ cell and Sertoli cells. Taken together, these data suggest that premature elevation in testosterone and persistently lower levels of circulating follicle stimulating hormone (FSH) are affecting Sertoli cell function, which is causing a reduced germ cell to Sertoli cell ratio in the YHR+ mice. These data suggest that the decrease in testis weight and seminiferous tubule diameter in YHR+ mine is due to a decrease in germ cell rather than Sertoli cell number.

No description available.

This study was undertaken to investigate the ultra-structure, cytochemistry and maturation changes of mink spermatozoa which are important in biological research and in their relevance to artificial insemination. Mature standard dark mink were used in this study. Spermatozoa were released from the testis and epididymis (caput, corpus and cauda) of the male mink, and were also collected from the vagina of female mink immediately after mating. Conventionally prepared thin sections were observed under a transmission electron microscope. Enzymes were cytochemically localized in spermatozoa. The mink spermatozoon head showed six swellings on the dorsoventral aspects: two connected hump-like structures at the anterior border of the equatorial segment of the acrosome, and one at the postacrosomal sheath on each side. These swellings, which show a strong acid phosphatase activity, appeared to be a species-specific structural feature which might be necessary for the recognition of the ovum or for sperm-ovum attachment in fertilization. The occurrence of the postacrosomal swelling in spermatozoa was significantly increased (p < 0.01) during the passage of spermatozoa through the reproductive tract. Although the total length of the head did not change significantly during the passage of spermatozoa down the reproductive tract, the anterior acrosomal length was significantly decreased (p < 0.001), while the postacrosomal length was significantly increased (p < 0.05). The cell membrane on the peripheral part of the acrosome, with the exception of the tip of the acrosome, was significantly separated (p < 0.05) during the passage of spermatozoa through the reproductive tract. The neck appeared to show dorsoventrally continuous but laterally separated capitulum which was followed by two major and five minor columns, forming at first a striated ring and then joining with the dense fibers.of the axial fiber bundle. Some axoneme remnants were found in the interior of the column bundle. The shape of the annulus was triangular in longitudinal sections. The occurrence of the cytoplasmic droplet was significantly decreased (p < 0.001) during the passage of spermatozoa through the test is and epididymis. The motility of spermatozoa was significantly increased (p < 0.05) as spermatozoa passed the successive parts of the reproductive tract. The activities of acid and alkaline phosphatases, ADPase, ATPase and DOPA oxidase were found to be distributed in the head, middle and principal pieces of epididymal spermatozoa. Glucose-6-phosphatase, 5-nucleotidase, non-specific esterase, malate, succinate, lactate and isocitrate dehydrogenases, and NADH diaphorase activities were seen to be confined to the middle piece, while the esterase and malate dehydrogenase activities extended to the head base. The activity of 6-phosphogluconic dehydrogenase was not detected. Although most enzyme activities of spermatozoa were enhanced during the passage of spermatozoa through the reproductive tract, several enzyme activities (acid and alkaline phosphatases, ADPase, ATPase, and malate dehydrogenase) were distinctly reduced in spermatozoa from ejaculated semen recovered from female mink following mating. The presence of enzyme inhibiting factors in the seminal plasma or female reproductive tract was discussed. / Land and Food Systems, Faculty of / Graduate