Cell interactions and genetic regulation that contribute to testicular Leydig cell development and differentiation.

Leydig cells, located within the interstitial compartment of the testis, are major contributors of androgen synthesis and secretion, which play an important role in testis development, normal masculinization, maintenance of spermatogenesis, and general male fertility. Accordingly, dysfunction of Leydig cells may lead to various male reproductive maladies, including primary hypogonadism, cryptorchidism, and hypospadias. A better understanding of how cell interactions and gene regulation contribute to testicular Leydig cell development and differentiation may therefore help limit the incidence of such male reproductive pathologies. Several hormones and signaling molecules have been identified as important regulators of Leydig cell differentiation and function. Recent work on the regulation of testis development, especially of Leydig cells, has focused on the Desert hedgehog and platelet-derived growth factor signaling pathways. This review outlines recent findings regarding cell interactions and gene regulation involved in the development and regulation of fetal and adult Leydig cell populations. Mol. Reprod. Dev. 83: 470-487, 2016. © 2016 Wiley Periodicals, Inc.

Embryonic pathogenesis of hypogonadism and renal hypoplasia in hgn/hgn rats characterized by male sterility, reduced female fertility and progressive renal insufficiency.

Congenital hypoplasia and dysplasia affect the postnatal development of organs, their physiological functioning in adulthood and the incidence of related diseases at an advanced age. Hypogonadic (hgn/hgn) rats are characterized by male sterility, reduced female fertility, progressive renal insufficiency and growth retardation, all controlled by a single recessive allele (hgn) located on chromosome 10. Since our previous studies indicated that the hypoplasia (dysplasia) of the affected organs was present at birth, we examined the embryonic pathogenesis. We mated hgn/hgn females to Brown Norway males and backcrossed F(1) males to hgn/hgn females. The resulting N(1) fetuses were genotyped using a hgn-linked microsatellite. Both sexes of hgn/hgn fetuses showed low body weight after embryonic day (ED) 15.5 and renal hypoplasia after ED 17.5. Their kidneys contained a reduced number of nephrons in a poorly formed nephrogenic zone and renal cortex. The hgn/hgn ovaries contained a small number of oogonia at ED 15.5 and oocytes after ED 17.5. Testicular growth defects were obvious after ED 17.5, and reduced numbers of Sertoli cells were detected at ED 19.5 and 21.5. The seminiferous cords in hgn/hgn testes contained more apoptotic and mitotic cells than those in +/hgn testes. These findings suggest that the phenotypes described in adult hgn/hgn rats result from embryonic hypogenesis, which continues to early postnatal stage and causes a reduction in functional tissues and cells. Since hgn/hgn rats have an insertion mutation in the microtubule-associated protein Spag5 gene, the embryonic hypogenesis described in hgn/hgn rats might result from defective cell proliferation.

Atypical development of Sertoli cells and impairment of spermatogenesis in the hypogonadal (hpg) mouse.

Testes of hypogonadal (hpg) mice show arrested postnatal development due to congenital deficiencies of gonadotrophin-releasing hormone (GnRH) and gonadotrophin synthesis and secretion. Follicle-stimulating hormone (FSH), androgen or oestrogen treatment restore qualitatively normal spermatogenesis in hpg testes. Understanding the cellular and molecular changes accompanying hormone-induced spermatogenesis in hpg mice requires detailed morphological analyses of the germ cells and Sertoli cells in the untreated hpg testis. We compared seminiferous epithelial cytology in adult hpg, immature and adult wild-type mice using unbiased optical disector-based stereology, immunolocalization of Sertoli cell microtubules (MT), espin (a component of the blood-testis barrier), markers of Sertoli cell maturity (p27(kip1) and WT-1), and electron microscopy. Hpg testes had marked reductions in weight, seminiferous cord volume and length, and severe spermatogenic impairment with germ cells per testis < 1% of adult wild-type testes. Sertoli cell nuclei expressed WT-1 in hpg testes, but often were centrally located, similar to 9-14-day-old wild-type testes, and they expressed p27(kip1), indicating that hpg Sertoli cells were post-mitotic. Hpg testes had significantly (P < 0.05) reduced Sertoli cells per testis (0.56 million) compared with 10-day wild-type (1.15 million) and adult wild-type testes (2.06 million). Immunofluorescence labelling of normal adult Sertoli cells showed supranuclear MT columns and basally located espin, but these features were absent in 10-day-old and hpg Sertoli cells. Hpg Sertoli cells showed pleomorphic nuclear ultrastructure with mature-type nucleoli, similar to normal adult-type Sertoli cells, but hpg Sertoli cells exhibited incomplete tight junctions that lacked ectoplasmic specializations. We conclude that in hpg mice, chronic gonadotrophin insufficiency restrains Sertoli cell proliferation and maturation, forming pseudo-adult-type Sertoli cells that are incapable of supporting germ cell proliferation and maturation.

Rathke's cleft cyst as a cause of growth hormone deficiency and micropenis.

Rathke's cleft cyst has rarely been reported in pediatric patients, and such cysts are usually found by chance, in 2-33% of routine necropsies, as they have not interfered with pituitary function. In general, they are intrasellar with a single layer of ciliated cuboidal or columnar epithelium containing mucoid material. The age range in which symptomatic Rathke's cleft cysts occur is between 30 and 60 years. This paper reports an 8.1-year-old boy presenting with growth hormone deficiency and micropenis attributable to hypogonadotropic hypogonadism (HH), implying altered pituitary function since intrauterine life. At this age (before puberty) the diagnosis of HH can be made by means of the LHRH agonist stimulation test, since conventional LHRH is not able to discriminate HH from a normal prepubertal child. To our knowledge, this is the first case of micropenis caused by Rathke's cleft cyst interfering with gonadotropin and growth hormone secretion since intrauterine life.

Xp duplications and sex reversal.

Male to female sex reversal has been observed in individuals with duplications of the short arm of the X chromosome. The study of Xp duplicated patients demonstrated that sex reversal results from the presence of two active copies of the DSS (dosage sensitive sex reversal) locus. A double dosage of DSS disrupts testis formation whereas its absence is compatible with a male phenotype, suggesting a role for DSS in ovarian development and as a link between ovary and testis formation. DSS was localized to a 160 kb region of Xp21, overlapping the adrenal hypoplasia congenita locus. The search for expressed sequences in the DSS critical region led to the identification of two types of genes: the DAM family and DAX-1, an atypical member of the nuclear receptor superfamily. Although no function is currently known for DAM genes, functional deficiency for DAX-1 has been shown to be responsible for adrenal hypoplasia congenita and hypogonadotropic hypogonadism. The search for the DSS gene(s) is still open and both the DAM genes and DAX-1 represent DSS candidate genes.

Cortically evoked motor responses in patients with Xp22.3-linked Kallmann's syndrome and in female gene carriers.

Patients with Kallmann's syndrome show hypothalamic hypogonadism, hyposmia, and congenital mirror movements. As a correlate, a defect of gonadotropic neuron migration into the brain was recently detected. Considering abnormal outgrowth of neurons also as a possible substrate underlying mirror movements, we studied 3 patients and 2 asymptomatic female gene carriers from a kindred with proven linkage to Xp22.3, using focal transcranial magnetic stimulation of motor cortex hand areas with a figure-eight coil. In all 3 affected brothers, bilateral responses could be evoked almost simultaneously in their thenar muscles (slight latency differences were statistically insignificant). In contrast, the mother and the maternal aunt showed only unilateral, normal thenar responses, even with maximum tolerable stimulator output and high signal amplification. Correspondingly, mirror movements were present in the patients, but not in the gene carriers. Bilaterality of cortically evoked hand muscle responses and mirror movements, therefore, behaved as X-chromosomal recessive traits. A likely cause might be a disorder of neuronal outgrowth in the motor system, particularly of inhibitory callosal fibers. For normal anatomical development of the motor system, one intact Xp22.3 gene seems necessary.

Kallmann syndrome associated with choanal atresia.

Kallmann syndrome is defined by the association of hypogonadotropic hypogonadism and anosmia. A previously unreported association of Kallmann syndrome and choanal atresia in a family is reported. The mechanism of the embryopathic association of hypogonadotropic hypogonadism, anosmia, and choanal atresia is though to be due to a single developmental field defect in the region of the median forebrain and associated structures. An irregular autosomal dominant mode of inheritance is suspected.

Gonadal development and gametogenesis in the hypogonadal mouse are restored by gene transfer.

These results describe controlled regulation of a mammalian neural gene in transgenic mice. Analysis of truncated GnRH-GAP genes in transgenic mice will enable us to define the DNA sequences responsible for this control. Furthermore, by separate mutation of the GnRH and GAP coding sequences we will be able to determine the relative importance of these two peptides in the development and maintenance of reproductive function.

A newly recognized neuroectodermal syndrome of familial alopecia, anosmia, deafness, and hypogonadism.

We describe a large, three generation kindred in which 16 individuals were affected with alopecia, hyposmia or anosmia, conductive deafness associated with protruding ears, microtia, and/or atresia of the external auditory canal, hypogonadotropic hypogonadism due to LH/FSH deficiency, and a greater than normal tendency to dental caries. Variable manifestations include mild facial asymmetry, mental retardation, congenital heart defect, and cleft palate. This seems to be a previously undescribed pleiotropic autosomal dominant trait with variable expressivity. The manifestations can be explained on the basis of involvement of the ectoderm and neuroectoderm of the first and second branchial arches, of Rathke's pouch, and of the diencephalon.

Micropenis. II. Hypogonadotropic hypogonadism.

This paper documents the case histories of 14 patients with hypogonadotropic hypogonadism and micropenis (penile length below 2.5 SD from the mean for the patient's chronlogical age, or for age corresponding to stage of sexual development). Nine of the patients were raised as males. Five of them received androgen for the purpose of stimulating penile growth: two realized normal adult penile length (-0.2 and -2.1 SD from normal mean length) whereas the other three had penile lengths significantly below the mean (-3.6, -4.6 and -5.2 SD from normal mean length). These data suggest that among hypogonadotropic patients with micropenis, those with prepubertal penile lengths between 2.5 and 3 SD below the mean may develop an adult penis of a length within the normal range. However, for those presenting with a shorter phallus, the expectation is that penile length will remain greater than 2 SD below the mean.

[Two cases of de Morsier's olfactogenital syndrome]. / Illustrazione di due casi di sindrome olfatto-genitale di de Morsier.

Two cases of De Morsier's olfactogenital syndrome (complex hypogenitalism and anosmia) are presented. The first patient was of eunuchoid build and presented testicle and penile hypotrophy, depressed adrenal activity and gonad-stimulating pituitary function and distinctly below-normal urinary 17-ketosteroid values. The second subject was gynaecoid, menopausal gonadotrophic hormonal values, short urethra with no radiological signs of the prostate, and gynaecoid upper pelvic basin diameters. The karyotype pattern was normal XY in the first case and XX in the second. It is suggested that embryopathic or genetic changes, probably in the rhinencephalon, led to a direct pituitary nervous short-circuit that impeded normal FSH gonadal stimulation and hence gonadal influence on the phenotype throughout both intra- and extrauterine life, particularly at puberty.