On the Embryonic Development of the Nasal Turbinals and Their Homology in Bats

Multiple corrugated cartilaginous structures are formed within the mammalian nasal capsule, eventually developing into turbinals. Due to its complex and derived morphology, the homologies of the bat nasal turbinals have been highly disputed and uncertain. Tracing prenatal development has been proven to provide a means to resolve homological problems. To elucidate bat turbinate homology, we conducted the most comprehensive study to date on prenatal development of the nasal capsule. Using diffusible iodine-based contrast-enhanced computed tomography (diceCT), we studied in detail the 3D prenatal development of various bat species and non-bat laurasiatherians. We found that the structure previously identified as “maxilloturbinal” is not the true maxilloturbinal and is only part of the ethmoturbinal I pars anterior. Our results also allowed us to trace the evolutionary history of the nasal turbinals in bats. The turbinate structures are overall comparable between laurasiatherians and pteropodids, suggesting that pteropodids retain the ancestral laurasiatherian condition. The absence of the ethmoturbinal I pars posterior in yangochiropterans and rhinolophoids has possibly occurred independently by convergent evolution.

Clinical and structural changes in reproductive organs and endocrine glands of sterile cows

Aim: The study aimed to determine both macroscopic and microscopic changes in the reproductive organs of sterile cows. Materials and Methods: Careful clinical and gynecological examinations (using histological and histochemical methods) of organs of culled sterile cows, such as ovaries, oviducts, the uterus, pars anterior adenohypophysis, thyroid body, and adrenals, were performed. Results: It was found that 20% of the examined cows in the farms of the Republic of Bashkortostan had pathology of reproductive organs. Ovarian dysfunction was diagnosed in 31% of sterile cows. Histological and histochemical studies revealed that high atresia of all types of ovarian follicles is associated with hypofunction of the ovaries. This was related to stromal vascular dystrophy and was accompanied by atrophy of thecal endocrine elements, resulting in decrease of endocrine and generative function of ovaries. Conclusion: Essential elements of the ovarian dysfunction pathogenesis are disorders of the functional system "ovary-pituitary-adrenal-thyroid gland" and the abnormality of utero-ovarian relationships, which differ significantly during hypofunction, in case of follicular cysts, and in case of persistent corpora lutea. This difference in abnormalities of utero-ovarian relationships should be considered when developing diagnostic and treatment methods and determining preventive measures.

The Aqueduct of Sylvius: Applied 3-T Magnetic Resonance Imaging Anatomy and Morphometry With Neuroendoscopic Relevance

BACKGROUND: The aqueduct of Sylvius (AqSylv) is a structure of increasing importance in neuroendoscopic procedures. However, there is currently no clear and adequate description of the normal anatomy of the AqSylv. OBJECTIVE: To study in detail hitherto unavailable normal magnetic resonance imaging morphometry and anatomic variants of the AqSylv. METHODS: We retrospectively studied normal midsagittal T1-weighted 3-T magnetic resonance images in 100 patients. We measured widths of the AqSylv pars anterior, ampulla, and pars posterior; its narrowest point; and its length. We recorded angulation of the AqSylv relative to the third ventricle as multiple deviations of the long axis of the AqSylv from the Talairach bicommissural line. We statistically determined age- and sex-related changes in AqSylv morphometry using the Pearson correlation coefficient. We measured angulation of the AqSylv relative to the fourth ventricle and correlated this to the cervicomedullary angle (a surrogate for head position). RESULTS: Patients were 13 to 83 years of age (45% male, 55% female). Mean morphometrics were as follows: pars anterior width, 1.1 mm; ampulla width, 1.2 mm; pars posterior width, 1.4 mm; length, 14.1 mm; narrowest point, 0.9 mm; and angulation in relation to the third and fourth ventricles, 26° and 18°, respectively. Age correlated positively with width and negatively with length of the AqSylv. There was no correlation between AqSylv alignment relative to the foramen magnum and the cervicomedullary angle. CONCLUSION: Normative dimensions of the AqSylv in vivo are at variance with published cadaveric morphometrics. The AqSylv widens and shortens with cerebral involution. Awareness of these normal morphometrics is highly useful when stent placement is an option during aqueductoplasty. Reported data are valuable in guiding neuroendoscopic management of hydrocephalus and aqueductal stenosis.

Histopathology of pituitary tumours

The human pituitary gland consists of two major components: the adenohypophysis comprising the hormone producing cells of the pars anterior, pars intermedia, and pars tuberalis, and the neurohypophysis, also called pars nervosa or posterior lobe (1). In contrast to most mammalian species, the human gland has no anatomically distinct pars intermedia (2). The exclusively proopiomelanocortin (POMC)-producing cells of the pars intermedia are sandwiched between the anterior and posterior lobes in the majority of mammals, whereas in the human they are incorporated within the pars anterior, thereby constituting the pars distalis (3). The pars tuberalis is a minor upward extension of the adenohypophysis attached to the exterior of the lower pituitary stalk. In this chapter we deal only with adenohypophyseal tumours. Histologically, the adenohypophysis consists of a central median (or mucoid) wedge flanked by the two lateral wings. The hormone-producing cell types are distributed in an uneven, but characteristic manner. The cells are arranged within evenly sized acini surrounded by a delicate but well-defined reticulin fibre network giving the pituitary its distinct architecture (4). In the center of the acini is the long-neglected pituitary follicle composed of the agranular nonendocrine folliculo-stellate cells (5).

Effects of Purified Polybrominated Biphenyl Congeners on the Thyroid and Pituitary Glands in Rats

Young male rats were fed diets containing 0, 1, 10, or 100 ppm of Firemaster (FM) BP-6 for 30 days and thyroidal and hypophyseal effects were compared with those caused by feeding identical amounts of either 2, 2', 4, 4', 5, 5'-hexabromobiphenyl (HBB) or 2, 3', 4, 4',5,5'-HBB, two of the congeners in FM BP-6. In addition, rats were given dietary levels of 0,1, or 10 ppm of 3,3', 4,4', 5, 5-HBB, a congener not in FM BP-6, but used because it is a 3-methylcholanthrene (MC)-type inducer of hepatic drug metabolizing enzymes. Thyroid weight was increased by 100 ppm FM BP-6 and by 1 and 10 ppm 3, 3', 4, 4', 5, 5'-HBB. Serum thyroxine concentrations were decreased by the highest dose of the same two chemicals. Extensive hyperplasia and hypertrophy of follicular cells and a lack of colloid were prominent lesions at the highest doses of each of the chemicals. The most severe ultrastructural alterations were seen at 10 ppm 3, 3', 4, 4', 5, 5'-HBB and 100 ppm FM BP-6. A dramatic increase in lysosomal bodies was seen at these doses. In addition, cytoplasmic colloid droplets were increased and microvilli were decreased. The Golgi apparatus was hypertrophied and the cisternae of the reticulum were dilated. Lesions were less severe with 2, 2', 4, 4', 5, 5-HBB and 2, 3', 4, 4', 5, 5-HBB, although more lysosomal bodies were seen with 2, 3', 4, 4', 5, 5-HBB than with 2, 2', 4, 4', 5, 5-HBB. Chromophobe cells in the pars anterior of the pituitary gland were swollen and vacuolated in rats fed diets containing 10 ppm 3, 3', 4, 4', 5, 5'-HBB. The results indicate that histologic and ultrastructural changes can occur with any of the chemicals used but the major functional and ultrastructural thyroidal changes seen in rats given FM BP-6 are most likely caused by congeners other than 2, 2', 4, 4', 5, 5-HBB or 2, 3', 4, 4, 5, 5-HBB.

Demonstration of desacetyl α-melanocyte-stimulating hormone in fetal and adult human anterior pituitary corticotrophs

ABSTRACT Immunocytochemistry, radioimmunoassay and high-performance liquid chromatography (HPLC) techniques have been used in combination to investigate the presence of immunoreactive (ir)-α-MSH in the normal human pituitary gland, and to investigate the possible origin of these cells from the fetal pars intermedia. Two separate antisera to α-MSH were employed in immunocytochemistry to distinguish between authentic α-MSH and the desacetyl form. Only desacetyl α-MSH was detected in the pituitary gland of fetal and adult man, in both the pars (zona) intermedia and the pars anterior. In the fetus, a large proportion of the ACTH-containing cells of the anterior lobe also contained ir-α-MSH, while ir-α-MSH containing cells were more sparse in adults. Radioimmunoassay of acid extracts of adult pituitary tissue showed α-MSH levels representing less than 0·05% of the ACTH content of the gland. HPLC analysis of these extracts confirmed that only the desacetyl form was present. These results suggest that α-MSH peptides are synthesized by anterior lobe cells of the human pituitary gland, which are not derived from the fetal pars intermedia. Possible regulatory mechanisms affecting cells which contain ir-α-MSH are discussed, and by comparison with the intermediate lobe of other species it is concluded that there is little evidence for a true intermediate lobe in the human pituitary gland. Journal of Endocrinology (1989) 120, 525–530

The distribution of immunoreactive α-melanocyte-stimulating hormone cells in the adult human pituitary gland

ABSTRACT It has been suggested that a proportion of the adenomas and the nodular hyperplasia of cells in the pituitary gland in cases of Cushing's disease are derived from cells of the pars intermedia rather than the pars anterior. The evidence can be summarized as follows: (1) the posterior site of adenoma or nodular hyperplasia in the pituitary, (2) the innervation of cells and (3) the suppressive response to the dopamine agonist bromocriptine in vivo or to dopamine in vitro. All these observations infer analogy with cells of the pars intermedia of other species, which are controlled by direct neural tonic dopaminergic inhibition. The adult human pituitary gland, however, does not possess a morphologically distinct pars intermedia, due to regression of the rudimentary fetal pars intermedia after birth, with mixing of cells into the pars anterior and pars nervosa. Since cells of the pars intermedia characteristically synthesize α-MSH, we have studied this peptide in order to assess the occurrence and distribution of intermedia-derived cells in the adult human pituitary. Sections from 100 pituitaries, removed at autopsy, were stained by an indirect immunoperoxidase technique using non-cross-reacting antisera specific for α-MSH and ACTH. Immunoreactive α-MSH (IR-α-MSH) cells were found in a total of 97 specimens. Of these, only ten cases showed a marked concentration of IR-α-MSH cells in the zona intermedia. In the majority of pituitaries, IR-α-MSH cells were more commonly seen in the pars anterior than in the zona intermedia; in 41 cases, IR-α-MSH cells were completely absent from the zona intermedia. The number of IR-α-MSH cells varied greatly, from less than ten cells per section to many hundreds, regardless of the age or sex of the individual. Additionally, no correlation could be made between the number of IR-α-MSH cells and the cause of death, treatment or the period of time between death and removal of the pituitary. We conclude that cells containing IR-α-MSH are present in varying numbers in the normal adult human pituitary gland. These cells do not show a specific distribution pattern, but may be found in both the zona intermedia and are spread throughout the pars anterior. J. Endocr. (1986) 111, 335–342

FUNCTIONAL SIGNIFICANCE OF THE CELLS IN THE PARS ANTERIOR OF THE PITUITARY GLAND OF THE MUSK SHREW (SUNCUS MURINUS L.)

Seven morphologically and tinctorially distinct types of cell (types 1–) have been distinguished in the pars anterior of the pituitary gland of the musk shrew (Suncus murinus L.). On the basis of their responses to various experimental stimuli, these cell types were correlated with the secretion of various trophic hormones. Type 1 cells exhibited conspicuous changes after thyroidectomy or inactivation of the thyroid gland and hence appeared to be the source of TSH. Types 2 and 3 cells responded to gonadectomy and administration of androgens, which suggests that they were associated with gonadotrophin secretion. The granules of the type 2, but not the type 3 cells could be extracted with 10% trichloroacetic acid, which may indicate that type 2 and 3 cells secrete FSH and LH respectively. After the administration of either reserpine or oestrogen, the type 4 cells underwent hypertrophy and hyperplasia, which suggests that they were the likely source of prolactin. Type 6 cells, which are distinguishable from type 4 cells by their thinly dispersed erythrosinophilic granulation, showed conspicuous changes after unilateral adrenalectomy, administration of metyrapone or exposure to stress and may therefore be responsible for secretion of ACTH. Type 5 cells tinctorially resembled the somatotrophic cells of other mammalian species and did not respond to any of the experimental treatments used in the present study. It is therefore possible that these cells have a somatotrophic function. The possible significance of type 7 cells has been discussed previously.