Precocene-induced sterility in F1 generation of Glossina morsitans morsitans

Precocene treatment does not disrupt the events of reproduction in Glossina morsitans morsitans or induce any apparent changes in treated tsetse. However, some females of the F₁ generation are either sterile or show retardations in follicle development. Sterility is not reversed spontaneously or with juvenile hormone analogues. The critical period for precocene action is related to each ovulation. The corpora allata of precocene-treated tsetse are normal, but those of F₁ sterile females are degenerate. The occurrence of retardation has enabled the characterisation of stages in follicle development in G. m. morsitans.     

The mode of regulation of the corpus allatum activity during starvation in adult females of the Colorado potato beetle, Leptinotarsa decemlineata (Say)

When two-day-old female Leptinotarsa decemlineata were starved, their corpus allatum activity, as measured by the radiochemical in vitro assay, was significantly reduced after 24 hr. Such a reduction was not observed when the nerve connections between the central nervous system and the retrocerebral complex were severed and the beetles starved up to 5 days. In some experiments, the rate of juvenile hormone biosynthesis in vitro, was substantiated by measurement of the juvenile hormone titre in the haemolymph by physico-chemical methods. It is concluded that intact nervous connections between the central nervous system and the corpora allata are essential for restraining the juvenile hormone biosynthesis during the initial stages of starvation.Corpora allata from 1-day starved insects were considerably stimulated in vitro by farnesenic acid indicating that juvenile hormone synthesis is controlled enzymatically at a stage prior to the final two steps in the pathway. However, on day 5 of starvation, rate-limitation may occur after formation of this intermediate, since farnesenic acid stimulation was much less at this time.Corpora allata of adult females newly emerged from the soil were activated within 4 hr regardless of feeding.     

Ultrasonic evaluation of the corpus luteum of the mare

Two distinct luteal morphologies were observed in the ovaries of mares studied by daily ultrasound examinations. Luteal glands that formed after 48.5% of 95 ovulations were uniformly echogenic over 90 to 100 percent of the area of the image of the gland throughout the period of detectability. The remaining luteal structures (51.5%) exhibited a centrally located nonechogenic area. The nonechogenic area was first detected on day 0 (28%), day 1 (62%), day 2 (6%) or day 3 (4%) postovulation. Glands classified as centrally nonechogenic were echogenic over 80 to 100 percent of the area of the image of the gland on day 0; mean percentages of echogenic tissue decreased to 45 percent by day three then gradually increased to 95 percent before the glands became unidentifiable. The echogenic portion of the luteal glands of both morphologies had a bright echogenicity (gray-scale zone 4.5 to 5) on day 0. The echogenicity decreased (zones 3 to 3.5) by day 8 and was maintained at approximately that level until day 12. Mean gray-scale values tended to increase (zone 4 to 4.5) prior to the time the luteal glands became ultrasonically unidentifiable. These changes in grayscale values may have reflected changes in luteal hemodynamics. The nonechogenic area of centrally nonechogenic glands was attributed to clotted blood (corpus hemorrhagicum). The formation of a corpus hemorrhagicum was apparently not functionally important because it was present in only one half of the luteal glands. In addition, the mean length of time that the luteal gland was identifiable (17 days) or the mean length of the interovulatory interval (21 days) was not significantly different between the two luteal morphologies. Therefore, the hypothesis that the formation of a corpus hemorrhagicum is a necessary step in luteogenesis was not supported.     

Progesterone synthesis and histology of postpartum bovine corpora lutea

In vitro progesterone (P(4)) synthesis by corpora lutea (CL) from the first, second or third ovulation after calving was compared and correlated with their histology and cytology. The CL were removed 7 to 12 days after ovulation, and luteal cells isolated by digestion with collagenase. The response of isolated cells to luteinizing hormone (LH) was determined. Hematoxylin-eosin stained tissues were used to study histology, and the distribution of cell types was estimated by stereological methods. Ovulation occurred within 25 days of calving and interovulatory intervals were short, 12.1 +/- 3.9 days and 12.6 +/- 4.8 days, respectively. The CL removed after first ovulation were smaller and contained fewer live cells than those obtained after subsequent ovulations. Stimulation by LH in vitro was independent of cycle number or day of cycle but was related to the histology of the tissue. The CL composed of large cells (> 24 mum) with vacuolated cytoplasm contained high amounts of P(4) but were not stimulated by LH. Conversely, CL composed of small and medium- sized cells (10 to 20 mum) and/or intact larger cells contained little P(4) but were stimulated by LH. These observations indicate that the response of postpartum CL to LH in vitro is dependent upon the structural integrity of the tissue at the time of removal. Furthermore, these observations suggest that the short life of CL during the postpartum period may not be due to the absence of luteotrophic support, but to the action of a luteolytic mechanism.     

The hormonal control of mitosis and meiosis during oögenesis in a blood-sucking bug Panstrongylus megistus

Total or partial ablation experiments were performed on the pars interecerebralis (P.I.), thoracic glands and corpus allatum of Panstrongylus megistus at two critical times during the initial development of the ovary: the periods before the mitotic crisis and before meiosis.Ablation of the P.I. clearly shows that ovarian mitoses and meiosis in the female P. megistus are two distinct phenomena, both dependent on the brain. Induction of mitosis is regulated by the A cells of the P.I. Once the mitotic crisis is over, these cells are no longer necessary for further ovarian development or, in particular, for the initiation of meiosis. The latter is dependent on the A cells of the P.I.The thoracic gland is not required for ovarian mitosis, but is indispensable for meiosis to occur. The corpus allatum has no influence on the differentiation of the ovariole but seems to be required for correct ovarian function during the cytoplasmic growth period of the oöcytes.     

A scanning electron microscopic study of the luteo-follicular complex

Summary As observed by SEM, the repair of an ovulated mammalian follicle is accompanied by a sequence of morphogenetic processes. In the initial phase, a mass of cells and coagulated fluids forms at the site of rupture. Shortly thereafter, connective cells, recruited from the adjacent and subjacent connective tissue stroma begin to proliferate and to migrate over this mass such that in the rabbit, the entire site of disruption is covered by a layer of connective cells by approximately 2 days following ovulation. Coincident with the migration of the connective tissue, superficial cells from undisturbed lateral and basal areas of an ovulated follicle also proliferate and begin to migrate over the newly established connective tissue matrix. By approximately 4 days following ovulation in the rabbit, the surface of an ovulated follicle is repopulated by elements of the superficial epithelium. The formation of the underlying corpus luteum (corpora luted) involves characteristic morphological changes as granulosa cells transform into steroid secreting luteal cells. The luteal cells become organized into cords of cells which usually surround capillary vessels. When examined by SEM, the smooth-surfaced endoplasmic reticulum of the luteal cell is quite apparent and is observed to form a three-dimension network of anastomosing tubules which are continuous with the nuclear membrane. Variations in the appearance of the surface of the ovary which directly overlies corpora lutea were observed when the mouse, rat and rabbit were compared. The regression of corpora lutea involves the infiltration of the luteal mass by connective tissue and both degeneration and vacuolization of the luteal cells. The regressing corpus luteum is a honey-comb-like structure in which each space is occupied by a degenerating luteal cell.This work was supported by grants from the National Institutes of Health, Public Health Service (to J.V.B., no. HD-04274), and from Consiglio Nationale delle Ricerche (C.N.R., contracts nos. CT 76.01288.04 and CT 77.01921.4)     

Prey capture efficiency in brown capuchin monkeys (Cebus apella) is influenced by sex and corpus callosum morphology

The diet of capuchin monkeys consists largely of fruits, but these monkeys commonly prey upon insects and other invertebrates as well as vertebrates such as lizards, birds, and fish. Capturing small fast‐moving prey requires the ability to process complex visuospatial information such as motion detection, shape, and pursuit. Here we report the results of an experimental investigation into whether capuchins display sex differences in prey capture efficiency, and whether these differences are associated with the morphology of regions of the corpus callosum (CC) involved in visuospatial ability. We examined the prey capture behavior of seven capuchin subjects (four female, three male) in the laboratory by providing subjects opportunities to fish. Additionally, we obtained structural magnetic resonance images from these subjects to determine if spatial‐ability was related to CC anatomy. Over 30 fishing trials, we recorded the number of prey capture attempts, success rate in capturing fish, and hand techniques used in these attempts. Males were significantly faster and more successful than females at capturing prey. In addition, males had smaller total CC:brain ratios than females. Males displayed a left hand bias, as well as significant unimanual usage, whereas females displayed no significant preference for hand usage. Individual capture times were correlated with total CC:brain ratio. Taken together, our results suggest a relationship between prey capture efficiency, sex, and the degree of brain lateralization. Am. J. Primatol. 72:502–508, 2010. © 2010 Wiley‐Liss, Inc.     

Effects of endogenous esterases and an allatostatin on the products of Manduca sexta larval corpora allata in vitro

Abstract A rapid and simple method has been developed for the simultaneous measurement of juvenile hormone (JH) and JH acid synthesized in vitro by larval corpora allata (CA) of the tobacco hornworm, Manduca sexta. An organic solvent partition of incubation medium efficiently separates JH acid from JH, and a radioimmunoassay which recognizes the two moieties equivalently is then employed to quantify each. The change in the biosynthetic product of the CA from JH to JH acid appears to begin slowly at the time of ecdysis to the last (fifth) larval stadium and is not complete until just prior to wandering (day 4). The inclusion of the JH esterase inhibitor S-benzoyl-O-ethyl phosphoramidothiolate in incubations of corpora allata revealed that the activity of JH esterases from the gland parallels gland activity and that significant hydrolysis of newly synthesized JH by these esterases occurs in incubations of glands taken at the beginnings of the fourth and fifth larval stadia. An allatostatin, which is proposed to inhibit the corpus allatum during the time of the change in its product, inhibits both JH I and JH I acid synthesis.     

Prenatal diagnosis of foetuses with congenital abnormalities and duplication of the MECP2 region

MECP2 duplication results in a well-recognised syndrome in 100% of affected male children; this syndrome is characterised by severe neurodevelopmental disabilities and recurrent infections. However, no sonographic findings have been reported for affected foetuses, and prenatal molecular diagnosis has not been possible for this disease due to lack of prenatal clinical presentation. In this study, we identified a small duplication comprising the MECP2 and L1CAM genes in the Xq28 region in a patient from a family with severe X-linked mental retardation and in a prenatal foetus with brain structural abnormalities. Using high-resolution chromosome microarray analysis (CMA) to screen 108 foetuses with congenital structural abnormalities, we identified additional three foetuses with the MECP2 duplication. Our study indicates that ventriculomegaly, hydrocephalus, agenesis of the corpus callosum, choroid plexus cysts, foetal growth restriction and hydronephrosis might be common ultrasound findings in prenatal foetuses with the MECP2 duplication and provides the first set of prenatal cases with MECP2 duplication, the ultrasonographic phenotype described in these patients will help to recognise the foetuses with possible MECP2 duplication and prompt the appropriate molecular testing.     

Diet and Mandibular Morphology in African Apes

Investigations seeking to understand the relationship between mandibular form, function, and dietary behavior have focused on the mandibular corpus and symphysis. African apes vary along a gradient of folivory/frugivory, yet few studies have evaluated the morphology of the mandibular corpus and symphysis in these taxa, and the investigations have yielded mixed results. Specifically, studies using external metrics have identified differences in mandibular proportions that analysis of cortical bone distribution has not substantiated. I contribute to the ongoing debate on the relationship between jaw form and dietary behavior by comparing mandibular corporal and symphyseal shapes in African apes. Importantly, and in contrast to previous studies of African ape internal geometry, I include the Virunga mountain gorillas (Gorilla beringei beringei), the ape most specialized toward a folivorous diet. I test the hypotheses that 1) Gorilla beringei beringei always has significantly more robust mandibular corpora and symphyses, relative to mandibular length, than all other African apes and 2) all gorillas have significantly more robust mandibular corpora and symphyses, relative to mandibular length, than Pan. Results demonstrate that the folivorous mountain gorillas consistently exhibit a relatively wider mandibular symphysis and corpus than all other African apes. Furthermore, all gorillas consistently exhibit relatively more robust mandibular corporal and symphyseal dimensions than Pan. The results indicate that among African apes, mountain gorillas are better able to counter lateral transverse bending (wishboning) loads at the symphysis and torsional loads at the corpus. All gorillas are likewise better able to resist wishboning and vertical bending at the symphysis, and sagittal bending and torsion at the corpus, than Pan, findings that are consistent with masticating relatively tougher foods, repetitive loading of the jaws, or both. I offer possible explanations for the lack of concordance in results between studies that have analyzed the biomechanical properties of African ape mandibles and others that have relied on external metrics. More comprehensive study of the internal geometry of the mandible is needed to resolve whether African apes differ morphologically in ways predicted by dietary variation.