Anterior Pituitary Function in Women with Postpartum Hemorrhage

Thirteen asymptomatic women with postpartum blood loss of at least 500 cc were evaluated for anterior pituitary endocrine function. Insulin tolerance tests and TRH stimulation tests were done and determinations made for serum growth hormone, cortisol, thyrotropin, and prolactin. There was no laboratory evidence of pituitary dysfunction in this group of 13 patients. Subclinical hypopituitarism in women with previous postpartum hemorrhage would appear to be uncommon.     

Combined Stain for Fish Pituitary

A new combined stain is described for the study of cell types in the fish pituitary. Tissues are prepared by fixing in formol-sublimate and then embedded in win wax. Tissue is sectioned at 5 μm and then stained sequentially with performic acid-alcian blue, periodic acid-Schiff, orange G, and acid fuchsin As a result of this procedure acidophils stain as follows: lactotropes, red; corticotropes, light pink melanotropes, bright pink and somatotropes, orange. Cyanophils stain either magenta red (gonadotropes) or blue (thyrotropes). Neurosecretory material and the fibers of the pars nervosa which penetrate the pars intermedia stain light blue.     

A Rhodocyan Technic for Staining the Anterior Pituitary

A reproducible, one-step, differential staining technic which uses routine formalin-fixed tissue and gives brilliantly contrasting results is produced by incubating sections for 1 hr in a 60° C oven in the following dye mixture: 1% eosin B (CI#771), 8 ml; 1% anilin blue (CI#707), 2 ml; and buffer solution (0.1M citric acid, 1.1 ml; 0.2M Na₂HPO₄, 0.9 ml; distilled water, 28.0 ml) at pH 4.5. No differentiation is necessary. The method can be modified for duodenal enterochromaffin cells and alpha cells of pancreatic islets by adjusting the buffer to pH 3.6 and staining for only 3 min at 60° C.     

Rhythmic and Nonrhythmic Modes of Anterior Pituitary Gland Secretion

Because of confounding effects of subject-specific and hormone-specific metabolic clearance, the nature of anterior pituitary secretory events in vivo is difficult to ascertain. We review an approach to this problem, in which deconvolu-tion analysis is used to dissect the underlying secretory behavior of an endocrine gland quantitatively from available serial plasma hormone concentration measurements assuming one- or two-compartment elimination kinetics. This analytical tool allows one to ask the following physiological questions: (a) does the anterior pituitary gland secrete exclusively in randomly dispersed bursts, and/or does a tonic (constitutive) mode of interburst hormone secretion exist? and (b) what secretory mechanisms generate the circadian or nyctohemeral rhythms in blood concentrations of pituitary hormones? Waveform-independent deconvolution analysis of 24-h serum hormone concentration profiles of immunoreactive growth hormone (GH), luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin, thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), and β-endorphin in normal men sampled every 10 min showed that (a) anterior pituitary gland secretion in vivo occurs in an exclusively burstlike mode for all hormones except TSH and prolactin (for the latter two, a mixed burst and basal mode pertains); (b) significant nyctohemeral regulation of secretory burst frequency alone is not demonstrable for any hormone; (c) prominent 24-h variations in secretory-burst amplitude alone are delineated for ACTH and LH; (d) TSH, GH, and β-endorphin are both frequency and amplitude controlled; (e) prolactin manifests 24-h rhythms in both secretory-burst amplitude and nadir secretory rates; (f) no significant diurnal variations occur in FSH secretory parameters; and (g) a fixed hormone half-life yields good fits of the 24-h serum hormone concentration series, which indicates that there is no need to introduce diurnal variations in hormone half-lives. In summary, the normal human anterior pituitary gland appears to release its various (glyco)protein hormones via intermittent secretory episodes that are apparently unassociated with significant basal hormone secretion, except in the case of TSH and prolactin. Hormone-specific amplitude and/or frequency control of secretory burst activity over 24 h provides the mechanistic basis for the classically recognized nyctohemeral rhythms in plasma concentrations of adenohypophyseal hormones in the human.     

Rhythmic and Nonrhythmic Modes of Anterior Pituitary Gland Secretion

Because of confounding effects of subject-specific and hormone-specific metabolic clearance, the nature of anterior pituitary secretory events in vivo is difficult to ascertain. We review an approach to this problem, in which deconvolu-tion analysis is used to dissect the underlying secretory behavior of an endocrine gland quantitatively from available serial plasma hormone concentration measurements assuming one- or two-compartment elimination kinetics. This analytical tool allows one to ask the following physiological questions: (a) does the anterior pituitary gland secrete exclusively in randomly dispersed bursts, and/or does a tonic (constitutive) mode of interburst hormone secretion exist? and (b) what secretory mechanisms generate the circadian or nyctohemeral rhythms in blood concentrations of pituitary hormones? Waveform-independent deconvolution analysis of 24-h serum hormone concentration profiles of immunoreactive growth hormone (GH), luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin, thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), and β-endorphin in normal men sampled every 10 min showed that (a) anterior pituitary gland secretion in vivo occurs in an exclusively burstlike mode for all hormones except TSH and prolactin (for the latter two, a mixed burst and basal mode pertains); (b) significant nyctohemeral regulation of secretory burst frequency alone is not demonstrable for any hormone; (c) prominent 24-h variations in secretory-burst amplitude alone are delineated for ACTH and LH; (d) TSH, GH, and β-endorphin are both frequency and amplitude controlled; (e) prolactin manifests 24-h rhythms in both secretory-burst amplitude and nadir secretory rates; (f) no significant diurnal variations occur in FSH secretory parameters; and (g) a fixed hormone half-life yields good fits of the 24-h serum hormone concentration series, which indicates that there is no need to introduce diurnal variations in hormone half-lives. In summary, the normal human anterior pituitary gland appears to release its various (glyco)protein hormones via intermittent secretory episodes that are apparently unassociated with significant basal hormone secretion, except in the case of TSH and prolactin. Hormone-specific amplitude and/or frequency control of secretory burst activity over 24 h provides the mechanistic basis for the classically recognized nyctohemeral rhythms in plasma concentrations of adenohypophyseal hormones in the human.     

Early Development of Mouse Anterior Pituitary: Role of Mesenchyme

Epithelial-mesenchymal interaction in the early development of the anterior pituitary gland was examined by chronological observations on fetal pituitary epithelium grafted in vivo with and without its own mesenchyme. At 8.5 days of gestation, the RATHKE'S pouch began to evaginate toward the diencephalon. The mesenchymal tissue around the pouch was at first very sparsely scattered, but then condensed, on day 10 becoming visible under a dissecting microscope. When RATHKE'S pouch epithelia from 10- and 12-day fetuses were transplanted alone under the kidney capsule, they proliferated slightly to form cysts, the cells of which differentiated into ACTH-producing cells, but not into prolactin-producing cells. Pituitary morphogenesis did not occur. When these epithelia were recombined with homotypic mesenchyme and transplanted, the epithelia proliferated remarkably on one side of the wall of the pouch, resulting in formation of a pars distalis that contained both ACTH-producing cells and prolactin-producing cells. Heterotypic mesenchyme, such as lung, dermis and mammary gland mesenchyme, could induce 12-day epithelium, but not 10-day epithelium to develop into pars distalis. Thus, fetal pituitary epithelium has the capacity of autodifferentiation into ACTH-producing cells, not into prolactin-producing cells, and requires mesenchymal support for development of the pars distalis.