Abstract
The gonads of the tammar wallaby, Macropus eugenii, are sexually indifferent at birth (Day 0) despite the fact that phenotypic sexual differentiation has already commenced as evidenced by the presence of a scrotum in males and mammary anlagen in females. The seminiferous cords of the testis first become clearly recognizable on Day 2 of pouch life, and ovarian differentiation is recognizable by Day 10. To monitor the endocrine development of the gonads during sexual differentiation of the urogenital tract, we measured the steroid hormone content in 92 pools of gonads from male and female tammar pouch young from the day of birth to 206 days of pouch life. Progesterone, estradiol, and dihydrotestosterone concentrations were low (<0.05 ng/mg protein) in both ovaries and testes at all stages examined, and testosterone concentrations were uniformly low in ovaries. Testosterone concentrations in testes were low on Days 0-4, averaging about 0.2 ng/mg protein; they rose by Days 5-10 to an average of 0.9 ng/mg protein, remained elevated until about Day 40, and thereafter fell to values similar to those in the ovaries. The phallus and urogenital sinus were able to convert testosterone to dihydrotestosterone from the earliest stages examined (Days 10 and 11). Thus in the tammar wallaby, as in eutherian mammals, testosterone is the androgen secreted by the developing testis, and dihydrotestosterone is formed in certain androgen target tissues. The finding that both the rise in testicular testosterone concentration and the capacity to form dihydrotestosterone in target tissues are demonstrable before the male urogenital tract begins to virilize suggests that the tissues initially lack the capacity to respond to these androgens. The fact that the development of a scrotum in the male or mammary anlagen in the female precedes a measurable increase in gonadal steroid concentrations is in keeping with the hypothesis that sexual dimorphism of the scrotum and mammary glands is not dependent on gonadal steroids.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 644-647 |
| Number of pages | 4 |
| Journal | Biology of Reproduction |
| Volume | 47 |
| Issue number | 4 |
| State | Published - 1992 |
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ASJC Scopus subject areas
- Cell Biology
- Developmental Biology
- Embryology
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Steroid hormone content of the gonads of the tammar wallaby during sexual differentiation. / Renfree, M. B.; Wilson, J. D.; Short, R. V.; Shaw, G.; George, F. W.
In: Biology of Reproduction, Vol. 47, No. 4, 1992, p. 644-647.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Steroid hormone content of the gonads of the tammar wallaby during sexual differentiation
AU - Renfree, M. B.
AU - Wilson, J. D.
AU - Short, R. V.
AU - Shaw, G.
AU - George, F. W.
PY - 1992
Y1 - 1992
N2 - The gonads of the tammar wallaby, Macropus eugenii, are sexually indifferent at birth (Day 0) despite the fact that phenotypic sexual differentiation has already commenced as evidenced by the presence of a scrotum in males and mammary anlagen in females. The seminiferous cords of the testis first become clearly recognizable on Day 2 of pouch life, and ovarian differentiation is recognizable by Day 10. To monitor the endocrine development of the gonads during sexual differentiation of the urogenital tract, we measured the steroid hormone content in 92 pools of gonads from male and female tammar pouch young from the day of birth to 206 days of pouch life. Progesterone, estradiol, and dihydrotestosterone concentrations were low (<0.05 ng/mg protein) in both ovaries and testes at all stages examined, and testosterone concentrations were uniformly low in ovaries. Testosterone concentrations in testes were low on Days 0-4, averaging about 0.2 ng/mg protein; they rose by Days 5-10 to an average of 0.9 ng/mg protein, remained elevated until about Day 40, and thereafter fell to values similar to those in the ovaries. The phallus and urogenital sinus were able to convert testosterone to dihydrotestosterone from the earliest stages examined (Days 10 and 11). Thus in the tammar wallaby, as in eutherian mammals, testosterone is the androgen secreted by the developing testis, and dihydrotestosterone is formed in certain androgen target tissues. The finding that both the rise in testicular testosterone concentration and the capacity to form dihydrotestosterone in target tissues are demonstrable before the male urogenital tract begins to virilize suggests that the tissues initially lack the capacity to respond to these androgens. The fact that the development of a scrotum in the male or mammary anlagen in the female precedes a measurable increase in gonadal steroid concentrations is in keeping with the hypothesis that sexual dimorphism of the scrotum and mammary glands is not dependent on gonadal steroids.
AB - The gonads of the tammar wallaby, Macropus eugenii, are sexually indifferent at birth (Day 0) despite the fact that phenotypic sexual differentiation has already commenced as evidenced by the presence of a scrotum in males and mammary anlagen in females. The seminiferous cords of the testis first become clearly recognizable on Day 2 of pouch life, and ovarian differentiation is recognizable by Day 10. To monitor the endocrine development of the gonads during sexual differentiation of the urogenital tract, we measured the steroid hormone content in 92 pools of gonads from male and female tammar pouch young from the day of birth to 206 days of pouch life. Progesterone, estradiol, and dihydrotestosterone concentrations were low (<0.05 ng/mg protein) in both ovaries and testes at all stages examined, and testosterone concentrations were uniformly low in ovaries. Testosterone concentrations in testes were low on Days 0-4, averaging about 0.2 ng/mg protein; they rose by Days 5-10 to an average of 0.9 ng/mg protein, remained elevated until about Day 40, and thereafter fell to values similar to those in the ovaries. The phallus and urogenital sinus were able to convert testosterone to dihydrotestosterone from the earliest stages examined (Days 10 and 11). Thus in the tammar wallaby, as in eutherian mammals, testosterone is the androgen secreted by the developing testis, and dihydrotestosterone is formed in certain androgen target tissues. The finding that both the rise in testicular testosterone concentration and the capacity to form dihydrotestosterone in target tissues are demonstrable before the male urogenital tract begins to virilize suggests that the tissues initially lack the capacity to respond to these androgens. The fact that the development of a scrotum in the male or mammary anlagen in the female precedes a measurable increase in gonadal steroid concentrations is in keeping with the hypothesis that sexual dimorphism of the scrotum and mammary glands is not dependent on gonadal steroids.
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M3 - Article
C2 - 1391352
AN - SCOPUS:0026761312
VL - 47
SP - 644
EP - 647
JO - Biology of Reproduction
JF - Biology of Reproduction
SN - 0006-3363
IS - 4
ER -