The anatomy and histology of XO human embryos and fetuses

Abstract

Thirteen abortuses with a known chromosomal complement of 45 (XO) were collected. Of these, eight contained an embryo or fetus ranging in age from five weeks to four months. Various gross anatomical abnormalities were evident in the four larger specimens and these included horseshoe kidney, unicornate uterus, single umbilical artery and cystic hygroma. One specimen had bilateral cystic hygromata. In all specimens, the gross anatomical appearance of the gonad was normal and, when examined histologically, the presence of primordial germ cells could be demonstrated. Histological sections of the XO gonads were compared with sections of gonads from known XX specimens of similar ages. There was no significant difference between the XO and XX gonads up to the third intrauterine month. In the older fetuses there was a relative increase in the connective tissue of the XO gonad. The finding of germ cells in the gonads of the XO fetuses is in contrast to the findings in XO adults who usually do not have germ cells in the gonads.

Outcomes of spontaneous and assisted pregnancies in Turner syndrome: the U.S. National Institutes of Health experience

“…Turner syndrome is caused by the absence of all or a significant portion of one sex chromosome during embryonic development, and is characterized by short stature and early ovarian failure in most affected individuals (2). Ovaries appear to develop normally in the 45X fetus, but accelerated atresia causes near complete follicle depletion by birth or early childhood (3-4). Sufficient follicles survive to allow for spontaneous menarche in 5-20% of girls with TS, although early menopause ensues (5-7).…”

A Diphasic Pattern of Gonadotropin Secretion in Patients with the Syndrome of Gonadal Dysgenesis

“…In patients with the syndrome of gonadal dysgenesis, normal or near-normal gonadal histology has been found up to the 4th month of gestation. Thereafter, impaired maturation and accelerated degeneration of gonadocytes results, with rare exceptions, in few if any germ cells in their gonads at birth (5).…”

Building Pathways for Ovary Organogenesis in the Mouse Embryo

“…The Y chromosome and its testis-determining element play an indisputable role in testis formation (see Chapter 2 on testis development). However, the number of X chromosomes is irrelevant to the establishment of the ovary, as humans and mice with XO aneuploidy still develop ovaries (Morris, 1968; Ohno and Cattanach, 1962; Singh and Carr, 1966, 1967; Welshons and Russell, 1959). …”