Hypophysectomized Male Rats Treated with Polydimethylsiloxane Capsules Containing Testosterone: Eftects on Spermatogenesis, Fertility, and Reproductive Tract Concentrations of Androgens

Buhl, Allen E.; Cornette, James C.; Kirton, K. T.; Yuan, Yang-Dar

doi:10.1095/biolreprod27.1.183

Cited by 54 publications

(21 citation statements)

References 13 publications

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“…The difference between these views resides in the lack of quantitative data on germ cell numbers in different endocrinological states available at the time of the earlier review. Although this process is testosterone dependent, it is important to note that the levels of testosterone required within the testis are only 10-15% of those in normal testis; as described previously by us (16) and others (12,(40)(41)(42)(43), spermiogenesis can be supported with considerably lower intratesticular testosterone levels than those observed in normal rats.…”

Section: Elongated Spermatidsmentioning

confidence: 71%

Quantitative Cytological Studies of Spermatogenesis in Intact and Hypophysectomized Rats: Identification of Androgen-Dependent Stages*

et al. 1990

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A stereological study of the numbers of germ cells in various stages of spermatogenesis was undertaken in testosterone-treated intact and hypophysectomized (HPX) rats. Adult Sprague-Dawley rats were given testosterone by Silastic implants, which either inhibited (3-cm length) or partially maintained (10 cm) spermatogenesis over a 13-week period. The numbers of nuclei of the various germ cell categories (spermatogonia, spermatocytes, and round spermatids) in the testes were estimated by profile counting and measurement of nuclear diameter. The numbers of elongated spermatids were determined separately in testicular homogenates. Testis weight, seminiferous tubule volume, and tubule diameter were significantly decreased in intact rats with 3- and 10-cm testosterone implants and in HPX rats, although they were partially maintained in groups with 10-cm implants compared to those in groups with 3-cm implants (P less than 0.05). The effect of 3-cm testosterone implants in the intact group was to suppress the number of spermatogonia to 57%, reduce the conversion of spermatogonia to spermatocytes to 85%, and reduce the conversion of round to elongated spermatids to 19% of the control value. This latter effect was largely overcome with 10-cm testosterone implants. In HPX rats, only 10-cm implants were effective in maintaining the conversion of round spermatids to elongated spermatids. However, testosterone alone was less effective in maintaining the conversion of spermatocytes to round spermatids, suggesting that a pituitary factor, probably FSH, was involved. It is concluded that testosterone has a major effect on the conversion of round to elongated spermatids. The conversion of spermatogonia to spermatocytes and the conversion of spermatocytes to round spermatids depend on the synergistic action of both FSH and testosterone. However, the effect of FSH is greatest on the conversion of spermatocytes to spermatids, i.e. meiosis.

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Section: Elongated Spermatidsmentioning

confidence: 71%

Quantitative Cytological Studies of Spermatogenesis in Intact and Hypophysectomized Rats: Identification of Androgen-Dependent Stages*

et al. 1990

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“…Earlier studies claimed that testosterone alone is capable of restoring spermatogenesis qualitatively in adults (Buhl et al 1982, Awoniyi et al 1992 without stimulating pituitary FSH (McLachlan et al 1994). Data from our laboratory demonstrated that FSH does not have the ability to rescue full spermatogenesis following chronic FSH and androgen action depletion in rats; however, mild increases in spermatogonia and flow on the effect of other germ cells up to pachytene spermatocytes have been observed (SM Ruwanpura, PG Stanton, DM Robertson, RI McLachlan, Y Makanji and SJ Meachem, unpublished observations).…”

Section: Long-term Studiesmentioning

confidence: 99%

Hormonal regulation of male germ cell development

Ruwanpura¹,

McLachlan²,

Meachem³

2010

Journal of Endocrinology

208

116

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Over the past five decades, intense research using various animal models, innovative technologies notably genetically modified mice and wider use of stereological methods, unique agents to modulate hormones, genomic and proteomic techniques, have identified the cellular sites of spermatogenesis, that are regulated by FSH and testosterone. It has been established that testosterone is essential for spermatogenesis, and also FSH plays a valuable role. Therefore understanding the basic mechanisms by which hormones govern germ cell progression are important steps towards improved understating of fertility regulation in health diseases.

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“…Although testosterone may be the driving force for spermatogenesis in the adult testis, FSH is probably still required to some extent (see also below), for although androgens on their own can maintain spermatogenesis (Ahmad, Haltmeyer & Eik-Nes, 1973;Buhl, Cornette, Kirton & Yuan, 1982) they cannot maintain normal testicular weight, implying that sperm production is subnormal in this case. The next question is: do the actions of FSH and testosterone on the Sertoli cell vary according to the stage of the spermatogenic cycle?…”

Section: The Hormonal Control Of Spermatogenesismentioning

confidence: 99%

Local Control of Testicular Function

Sharpe

1983

Exp Physiol

124

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This review has shown that local control of testicular function exists at three different levels. (1) Regulation of the entry of substances into the testis via the operation of selective barriers at the level of the capillary endothelium, myoid layer and Sertoli cell tight junctions, and by control of the rate of interstitial fluid formation which is the medium for transport into and within the testis. These mechanisms permit the creation of specific micro‐environments around the Leydig cells and outside of the seminiferous tubules as well as within the tubules, prerequisites for the local interaction and communication summarized below. (2) Regulation of spermatogenesis by co‐ordination of changes in hormone responsiveness and function of the Sertoli cells with the requirements of the associated germ cells, this varying according to the stage of the spermatogenic cycle. These changes involve regulation of germ cell multiplication, their differentiation and translocation from the basal to the adluminal compartment of the seminiferous tubule and their release into the lumen. (3) Interaction between the seminiferous tubules and the Leydig cells via various factors. The purpose of this interaction is not certain but in the prepubertal testis it probably co‐ordinates development of the tubules and Leydig cells, whilst in the adult testis it probably functions to regulate the steroidogenic responsiveness of the Leydig cells in accordance with the stage‐dependent requirements of the adjacent seminiferous tubules. Local control mechanisms within the testis therefore appear to co‐ordinate the function of the different cell types in the two testicular compartments and, as this is essential for normal function of the testis, the importance of local factors is self‐evident. In each of the three areas there is still only limited information as to the precise operation of the various mechanisms and even less is known about the identity of the co‐ordinating agents. But, as most of the available information derives only from the last three years, the gaps in our knowledge are to be expected and it is certain that the next few years will see major advances in this area. If the interpretation of the data offered in this review proves accurate then we are on the threshold of a revolution in our understanding of the control of testicular function, and of spermatogenesis in particular. This can only lead to improved methods for regulation of fertility in the male.

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Hypophysectomized Male Rats Treated with Polydimethylsiloxane Capsules Containing Testosterone: Eftects on Spermatogenesis, Fertility, and Reproductive Tract Concentrations of Androgens

Cited by 54 publications

References 13 publications

Quantitative Cytological Studies of Spermatogenesis in Intact and Hypophysectomized Rats: Identification of Androgen-Dependent Stages*

Quantitative Cytological Studies of Spermatogenesis in Intact and Hypophysectomized Rats: Identification of Androgen-Dependent Stages*

Hormonal regulation of male germ cell development

Local Control of Testicular Function

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