Immature spermatids are not prevalent in semen from men who are receiving androgen-based contraceptive regimens

Yang, Zhengwei; Wreford, Nigel G.; Bremner, William J.; Matsumoto, Alvin M.; Anawalt, Bradley A.; McLachlan, Robert I

doi:10.1016/s0015-0282(97)00426-3

Cited by 14 publications

(13 citation statements)

References 31 publications

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“…5, although total germ cell number was not correlated to Sertoli cell number in the removed testis, in accord with an earlier finding (150), this relationship became highly significant in the remaining testis. Although unilateral orchidectomy is performed in cases of testicular cancer, torsion, and trauma, it is difficult to generalize on the impact of this surgical procedure on the remaining testis because of the heterogeneity of the subjects and the lack of information on testicular function before unilateral orchidectomy (151)(152)(153)(154)(155).…”

Section: F Regulation Of Sperm Numbersupporting

confidence: 86%

The Functional Significance of FSH in Spermatogenesis and the Control of Its Secretion in Male Primates

Plant¹

2001

Endocrine Reviews

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The aim of this review is to provide an integrative analysis of the role of FSH in the control of testicular function in higher primates, including man. Attention is focused on the action of FSH during neonatal development, puberty, and adulthood. Whether FSH is the major determinant of the adult complement of Sertoli cells and whether FSH is obligatory for the initiation, maintenance, and restoration of spermatogenesis is evaluated. The mechanism whereby the circulating concentration of FSH regulates spermatogonial proliferation to dictate the sperm production rate under physiological conditions in the adult is discussed in detail. Inhibin B is the major component of the testicular negative feedback signal governing FSH␤ gene expression and FSH secretion, and the evidence for this view is presented. The review concludes with the presentation of a model for the operation of the FSHinhibin B feedback control system regulating sperm production postpubertally in monkey and man, and with speculation on issues of clinical interest. (Endocrine Reviews 22: 764 -786, 2001)

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Section: F Regulation Of Sperm Numbersupporting

confidence: 86%

The Functional Significance of FSH in Spermatogenesis and the Control of Its Secretion in Male Primates

Plant¹

2001

Endocrine Reviews

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“…Some authors suggest the existence of a population of A transition -spermatogonia. These show histological characteristics which allow to assume that these spermatogonia occupy an intermediate position between the A dark -and the A pale -spermatogonia (Clermont & Leblond 1959, Clermont 1969, Clermont & Antar 1973, Kluin et al 1983, Fouquet & Dadoune 1986, van Alphen et al 1988a, Zhengwei et al 1997. The distinction between A dark -and A pale -spermatogonia relies on adequate fixation, embedding, and staining techniques, and on the morphological recognition of delicate histological details.…”

Section: Spermatogonial Subtypes In Primatesmentioning

confidence: 99%

“…In the second study, in which tritiated thymidine was employed to detect cells in S-phase at different stages of the seminiferous cycle of Cercopithecus aethiops, it is not unlikely that the radiation emitted from the small number of proliferating A pale -spermatogonia going through S-phase at stage VII has been masked by the high radiation emission from a much larger number of preleptotene spermatocytes going through S-phase prior to meiosis at exactly the same stage. In addition, Fouquet & Dadoune (1986), and Zhengwei et al (1997) presented data on spermatogonial renewal and spermatogenesis in a fourth species of nonhuman primates, the crab-eating macaque (Macaca fascicularis). The former demonstrated two peaks of mitoses of A pale -spermatogonia in this species during one spermatogenic cycle.…”

Section: Spermatogonial Subtypes In Primatesmentioning

confidence: 99%

A revised model for spermatogonial expansion in man: lessons from non-human primates

Ehmcke¹,

Schlatt²

2006

Reproduction

157

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We have recently described a revised scheme for spermatogonial expansion in non-human primates. We proposed that A palespermatogonia act as self-renewing progenitors and premeiotic germ cells are organized and divide as small clones. Here, we are revisiting the model described for man and propose a modified scheme for spermatogonial expansion. Our revised model shows high similarity to the scheme proposed for non-human primates and is in accordance with all previous and present data.

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“…Although some round spermatids are seen in ejaculates of men following gonadotropin withdrawal, their number is low and does not correlate with the rapid fall in sperm count (Zhengwei et al, 1998a). However, it is important to note that T treatment suppresses both LH and FSH in man, a situation that is analogous to the GnRH-immunised rat, where spermiogenesis is fully suppressed prior to the production of step 8 spermatids (see Figures 1 and 2).…”

Section: B the Regulation Of Spermiogenesismentioning

confidence: 99%

Identification of Specific Sites of Hormonal Regulation in Spermatogenesis in Rats, Monkeys, and Man

McLachlan

O’Donnell²,

Sj³

et al. 2002

Recent Progress in Hormone Research

366

243

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A detailed understanding of the hormonal regulation of spermatogenesis is required for the informed assessment and management of male fertility and, conversely, for the development of safe and reversible male hormonal contraception. An approach to the study of these issues is outlined based on the use of well-defined in vivo models of gonadotropin/androgen deprivation and replacement, the quantitative assessment of germ cell number using stereological techniques, and the directed study of specific steps in spermatogenesis shown to be hormone dependent. Drawing together data from rat, monkey, and human models, we identify differences between species and formulate an overview of the hormonal regulation of spermatogenesis. There is good evidence for both separate and synergistic roles for both testosterone and follicle-stimulating hormone (FSH) in achieving quantitatively normal spermatogenesis. Based on relatively selective withdrawal and replacement studies, FSH has key roles in the progression of type A to B spermatogonia and, in synergy with testosterone, in regulating germ cell viability. Testosterone is an absolute requirement for spermatogenesis. In rats, it has been shown to promote the adhesion of round spermatids to Sertoli cells, without which they are sloughed from the epithelium and spermatid elongation fails. The release of mature elongated spermatids from the testis (spermiation) is also under FSH/testosterone control in rats. Data from monkeys and men treated with steroidal contraceptives indicate that impairment of spermiation is a key to achieving azoospermia. The contribution of 5␣-reduced androgens in the testis to the regulation of spermatogenesis is also relevant, as 5␣-reduced androgens are maintained during gonadotropin suppression and may act to maintain low levels of germ cell development. These concepts are also discussed in the context of male hormonal contraceptive development.

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Immature spermatids are not prevalent in semen from men who are receiving androgen-based contraceptive regimens

Cited by 14 publications

References 31 publications

The Functional Significance of FSH in Spermatogenesis and the Control of Its Secretion in Male Primates

The Functional Significance of FSH in Spermatogenesis and the Control of Its Secretion in Male Primates

A revised model for spermatogonial expansion in man: lessons from non-human primates

Identification of Specific Sites of Hormonal Regulation in Spermatogenesis in Rats, Monkeys, and Man

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