Charles A. Singhas

Hormonal control of the tail fin and of the nuptial pads in the male red-spotted newt

Abstract Seasonal variation in tail fin height and in display of nuptial pads has been followed in the red-spotted newt ( Notophthalmus viridescens viridescens ), and various experiments have been conducted to elucidate the hormonal control of those structures. The height of the tail is constant in the female, but in the autumn that of the male increases to maximal proportions and black, keratinized nuptial pads form on the hind legs. At the end of the spring breeding season these nuptial pads are lost and the tail fin is markedly reduced in height. A similar loss of pads and decline in tail height takes place whenever pad-bearing males are brought into the laboratory and kept at room temperature with long day lengths. Loss of tail height was apparently unaffected by thyroidectomy or by the administration of testosterone on alternate days, but its decline was slowed by autografting the pituitary gland and was halted by the administration of prolactin on alternate days. Tail height of laboratory-conditioned male newts was restored over a period of 2–3 wk by the administration of prolactin. In hypophysectomized, conditioned males the response of the tail fin to prolactin was greatly reduced but was restored to a considerable extent by the additional administration of thyroid hormone or thyroid stimulating hormone. In intact animals the loss of nuptial pads was delayed by autografting of the pituitary gland, by thyroidectomy, and by the administration of prolactin. It was unaffected by testosterone, but was prevented by prolactin and testosterone given in combination. The combined dose also induced restoration of pads after their regression in laboratory-conditioned males. In hypophysectomized, laboratory-conditioned males thyroxine or thyroid stimulating hormone was required in addition to prolactin and testosterone for the restoration of nuptial pads. Luteinizing hormone, but not progesterone, was an effective substitute for testosterone.

Prolactin binding sites on human chorion-decidua tissue

Abstract An effective procedure has been developed and utilized to demonstrate the presence of prolactin receptors on the plasma membranes of human chorion-decidua cells. Particulate fractions from human chorion-decidua sedimenting between 1,500 and 45,000 × g display optimal binding of 125 I-labeled ovine prolactin when incubated at a membrane protein concentration of 200 μg per assay tube for 2 hours at 22° C. Specific binding was increased by pretreatment of the membrane particles with 5M magnesium chloride to remove endogenous prolactin. These receptors show binding parameters (affinity, 0.92 × 10 9 L/mole; capacity, approximately 80 fmoles/mg) similar to those of lactogenic receptors in the rabbit mammary gland and, the rabbit and rat liver. The presence of prolactin receptors in human chorion-decidua suggests they may play a role in mediating local action(s) of prolactin such as involvement in the decidualization reaction or in maintaining fetal osmoregulation.

The developmental cytology of the nuptial pad in the red-spotted newt☆

Abstract The ultrastructure of developing, mature and regressing nuptial pads has been examined and interpreted in the red-spotted newt. The development of the pad begins with a thickening of the dermis. Mitotic activity then increases the cell layers of the epidermis from about four to approximately eight. Simultaneously, keratinocytic synthetic activity shifts to produce more tonofilaments and fewer mucous granules. In the upper cell layers, the shift is followed by an increase in cytoplasmic volume with bundles of tonofilaments accumulating on the anterior side of each cell, displacing the nucleus posteriorly. After this rearrangement, the enlarged cells become grouped into ascending columns that tilt posteriorly from the basal epidermal layer at an angle of about 45°. Also the flattened cells of the monolayered stratum corneum become superficially roughened and with successive molts are replaced by orderly rows of cornified conical structures possessing cusps that are directed posteriorly. Each cone then lies at the top of one of the germinative columns. In rudimentary pads induced on female newts, the epidermis attains a height of only five or six layers and columns are not evident, but other developmental features of the male are present. During regression, mitosis is slowed and the developmental sequence is reversed.

Prolactin secretion by human chorion-decidua in vitro: Influences of mode of delivery and agents that modify prostaglandin synthesis

Prolactin production by human decidua was examined with the use of a short-term tissue explant system. Decidua obtained after normal spontaneous vaginal deliveries produced significantly more prolactin than did tissue obtained after elective repeat cesarean section deliveries in the absence of labor (P less than 0.005). Cytosolic prolactin levels did not differ between the two delivery modes. Oxytocin (4.3 X 10(-11) M to 4.3 X 10(-6) M) and eicosatetraenoic acid (10(-7) M to 10(-4) M) had no effect on prolactin production or storage by decidual tissue. Indomethacin at 10(-4) M reduced only levels of stored prolactin but had no effect on stored or produced prolactin at lower concentrations (10(-7) M to 10(-5) M). Arachidonic acid (10(-4) M) suppressed both production and storage of prolactin (P less than 0.05). Decidual tissue from the two delivery modes did not differ in response to the above agents. Although the exact mechanism(s) remains obscure, these results indicate decidual prolactin production is altered by some aspect of labor. The possible involvement of prostaglandin precursors in mediating this production cannot be excluded.

Effect of betamethasone on fetal macrophage function: depression of adherence of immunoglobulin-coated red blood cells.

ABSTRACT: In this study, betamethasone was found to significantly inhibit the binding of immunoglobulin‐coated O Rh‐positive red cells to fetal macrophages. At a dose of 0.15 mg%, betamethasone depressed immune rosette formation to 44% of controls (p < 0.01); and a dose of 0.60 mg% resulted in an average depression to 22%. This in vitro effect may reflect important alterations in in vivo immune function in infants delivered from mothers who have received antenatal corticosteroids.

Hyperpigmented patches in the skin of the newt Notophthalmus viridescens

In the integument of the red-spotted newt there occasionally appear patches of skin which are at the same time melanistic and iridescent. Such hyperpigmented patches have been found on the back, on the tail and on the dorsal surface of both fore and hind limbs. Cytological examination of several such areas revealed the presence of large numbers of chromatophores distributed throughout the dermis. The majority of the chromatophores consisted of atypically large and dendritic melanophores, which contained typical pigment granules. The iridescence resulted from a high incidence of iridophores. Xanthophores also were found in considerable abundance. This extensive and apparently random intermingling of melanophores, iridophores and xanthophores in limited areas constitutes a striking exception to the usual distributional patterns of pigment cells in this animal.

Prolactin Binding Sites on Human Chorion-Decidua Tissue

An effective procedure has been developed and utilized to demonstrate the presence of prolactin receptors on the plasma membranes of human chorion-decidua cells. Particulate fractions from human chorion-decidua sedimenting between 1,500 and 45,000 x g display optimal binding of 215I-labeled ovine prolactin when incubated at a membrane protein concentration of 200 micrograms per assay tube for 2 hours at 22 degrees C. Specific binding was increased by pretreatment of the membrane particles with 5M magnesium chloride to remove endogenous prolactin. These receptors show binding parameters (affinity, 0.92 x 10(9) L/mode; capacity, approximately 80 fmoles/mg) similar to those of lactogenic receptors in the rabbit mammary gland and, the rabbit and rat liver. The presence of prolactin receptors in human chorion-decidua suggests that may play a role in mediating local action(s) of prolactin such as involvement in the decidualization reaction or in maintaining fetal osmoregulation.

Ultrastructural Observations of the Time Sequence of Induction of Acrosomal Membrane Alterations by Ovarian Follicular Fluid**Supported by United States Public Health Service Grant RO1-HD08573.

Ultrastructural studies were made of rabbit sperm pretreated with high ionic strength medium and fixed after 0, 5, 10, 15, and 30 minutes of incubation in bovine follicular fluid (BFF) or control medium. Membrane changes associated with loss of the acrosomal contents were divided into three stages: membrane fusion; a vesiculation stage where approximately 50% of the contents of the acrosome were lost; and completion, where the outer acrosomal membrane and adjacent plasma membrane were lost. The rate of each step appeared to be independent of the subsequent phase, since no steady-state concentration was seen for any of the stages during the reaction. After 5 minutes exposure to BFF, multiple fusions and vesiculations had occurred which involved the plasma and outer acrosomal membranes. After 10, 15, and 30 minutes of incubation, increasing numbers of sperm showed fusion and the formation of vesicles. By 30 minutes, 37/100 sperm showed vesicle formation and an additional 30% showed complete loss of vesicles and the acrosomal contents. The inner acrosomal membrane, nuclear membrane, and membranes posterior to the equatorial segment were unaffected by this treatment, as were all membranes after 30 minutes in control medium. The sequence of events indicated by these observations suggests that the BFF-induced acrosome reaction may be similar to that occurring in vivo to sperm in juxtaposition to ova.