Ontogeny of the sexually dimorphic male nucleus in the preoptic/anterior hypothalamus of ferrets and its manipulation by gonadal steroids.
A sexually dimorphic nucleus exists in the dorsal region of the ferret preoptic/anterior hypothalamic area (POA/AH), and is called the male nucleus of the POA/AH (MN-POA/AH) because it is found only in males. Development of the MN-POA/AH was studied in male ferrets, and for comparison a sexually nondimorphic ventral POA/AH nucleus was studied in both sexes. The MN-POA/AH was conspicuous in males as early as embryonic day 37 (E37) of a 41-day gestation, and its volume increased until postnatal day 56 (P56). No nucleus was present in the dorsal POA/AH of females at any age. The densities and average somal areas of cells in the dorsal POA/AH were similar in males and females at E33, before the MN-POA/AH could be visualized. However, at E37 and E41 dorsal cells were greater in density and/or somal area in males than in females, accounting for the appearance of a nucleus in males at these ages. To insure that the dorsal POA/AH nucleus seen in males at E37 and E41 was the presumptive MN-POA/AH present in adult males, pregnant ferrets were given progesterone and either implanted subcutaneously (s.c.) with testosterone (T) or ovariectomized and implanted s.c. with the aromatase inhibitor, 1,4,6-androstatriene-3,17-dione (ATD), on day 30 of gestation. As predicted from previous studies in which subjects were sacrificed in adulthood, formation of a dorsal POA/AH nucleus was promoted in female ferrets by T, and blocked in males by maternal ovariectomy and ATD treatment for animals sacrificed at E41. Much evidence suggests that behavioral sexual differentiation is accomplished in the male ferret between age E28 and P20. The MN-POA/AH is present and potentially functional in males during a considerable portion of this perinatal period.
Cherry
J A
JA
Department of Biology, Boston University, Massachusetts 02215.
Basham
M E
ME
Weaver
C E
CE
Krohmer
R W
RW
Baum
M J
MJ
D000733:Androstatrienes / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D047072:Aromatase Inhibitors; D004967:Estrogens / Q000494:pharmacology; D005260:Female; D005289:Ferrets / Q000033:anatomy & histology* / Q000196:embryology / Q000254:growth & development; D012739:Gonadal Steroid Hormones / Q000494:pharmacology*; D007032:Hypothalamus, Anterior / Q000187:drug effects* / Q000196:embryology / Q000254:growth & development; D008297:Male; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D011301:Preoptic Area / Q000187:drug effects / Q000196:embryology / Q000254:growth & development; D011374:Progesterone / Q000494:pharmacology; D012727:Sex Characteristics; D012726:Sexual Behavior, Animal / Q000502:physiology; D013739:Testosterone / Q000494:pharmacology
D000733:Androstatrienes; D047072:Aromatase Inhibitors; D004967:Estrogens; D012739:Gonadal Steroid Hormones; C011658:androsta-1,4,6-triene-3,17-dione; D013739:Testosterone; D011374:Progesterone