Plasma Testosterone Concentrations during Postnatal Development in the Male Common Marmoset

Abstract

Repeated measurements of plasma testosterone (T) were made in 56 male marmosets from the day of birth until 300 days of age and in 44 adults (>3 years). The resulting profile of plasma T during postnatal development shows higher levels during infancy (1–90 days) followed by a nadir between 100 and 170 days and then a progressive rise in T during puberty. Although T levels of up to 21 ng/ml were measured in infant males, mean levels (±SEM) were 5.4 ± 0.6 ng/ml (days 1–10), declining gradually to 1.7 ± 0.1 ng/ml (days 100–110). No increase in mean T levels between 15 and 100 days was identified, and the onset of puberty was earlier in some males than measured previously in this species.

Testicular Volume and Reproductive Status of Wild Callithrix jacchus

“…The body and testicular development curves that we obtained are in accordance with the typical pattern for anthropoid primates, with rapid neonatal growth, a slow juvenile phase, and a second peak of rapid development during adolescence (Plant 1988). Body mass values in the adult subjects were similar to those previously described (captivity: Abbott and Hearn 1978;wild: Araújo et al 2000) and to those of captives observed for testicular volume (Abbott and Hearn 1978;Dixson 1986). Testicular volume in infants and juveniles is similar but a rapid increase occurred between the juvenile and subadult ages, reaching, as expected, the highest values in adulthood.…”

“…Increased testicular volume in adults is related to increased spermatogenetic activity, testosterone production, and spermatozoid maturation (Li et al 2005). The relatively high testicular volume in the infantile stage is also coincident with the peak of testosterone production from birth until the 110th day in male common marmosets (Dixson 1986). It is important to note that we measured the testis when the individuals were 3-5 mo old because the fully descended testes in callitrichids occurs around then (Saguinus oedipus oedipus: 8 wk, Ginther et al 2002;Callithrix jacchus: 50-70 d, Abbott and Hearn 1978).…”

Changes in endocrine profile and reproductive organs during puberty in the male marmoset monkey (Callithrix jacchus)

“…In the single comparison of intratesticular with serum testosterone, taken just prior to the removal of organs, the moderate positive correlation at least rules out the assays themselves as a source of fluctuation. Extreme individual variations in testosterone concentrations have been reported previously (Dixson 1986, Lunn et al 1994. Marmosets have been shown to have sex hormone binding globulin.…”

Immunocytochemical Localization of Bioregulatory Peptides in Marmoset Testes

“…Activity of the Leydig cells is maximum at birth and puberty. Between these two peaks there is a period of quiescence, reflected by testosterone production [ 5 ] .…”