Birgit Kemp

Ontogenesis of the sperm whale brain

The development of the sperm whale brain (Physeter macrocephalus) was investigated in 12 embryos and early fetuses to obtain a better understanding of the morphological and physiological adaptations in this most exotic cetacean concerning locomotion, deep diving, and orientation. In male adult sperm whales, the average absolute brain mass and the relative size of the telencephalic hemisphere are the largest within the mammalia, whereas the ratio of the brain mass to the total body mass is one of the smallest.

Dendritic cells are equally distributed in intrauterine and tubal ectopic pregnancies

OBJECTIVE To examine different stages of dendritic cells (DCs) in intrauterine (IUPs) and viable tubal (VTPs) pregnancies to further elucidate mechanisms of fetomaternal tolerance and extravillous trophoblast invasion. DESIGN Experimental study on patient-controlled material. SETTING University hospital. PATIENT(S) Seven women with normal IUPs and ten with VTPs in the first trimester. INTERVENTION(S) Suction curettage in IUP, laparoscopy in VTP. MAIN OUTCOME MEASURE(S) Immunohistochemistry for cytokeratin-7 (trophoblast), CD83 (mature DCs), DEC205 (activated but not fully mature DCs), DC-SIGN (immature macrophage-like DCs), and CD14 (macrophages) alone and in double staining. RESULT(S) The numbers of CD83+ and DEC205+ cells were similarly low in IUP and VTP (0.83 and 0.44 cells/mm2; 2.28 and 2.96 cells/mm2). The number of DC-SIGN+ cells was higher, though without significant differences among the entities examined (57.5 and 47.4 cells/mm2). About two-thirds of DC-SIGN+ cells were also CD14+ in IUP and VTP. CONCLUSION(S) The almost equal distribution of CD83+, DEC205+, and DC-SIGN+ cells in IUP and VTP suggests analogue control mechanisms in intrauterine and extrauterine DC differentiation and a comparable role of these DCs for the development of fetomaternal tolerance.

Is cervical dilatation during parturition at term associated with apoptosis

Abstract Aims: Cellular turnover may be involved in remodeling of the cervix during parturition. Therefore, the number and localization of apoptotic and proliferating cells during cervical dilatation at term were determined. Methods: Biopsy specimens from the lower uterine segment of 36 women undergoing cesarean section with a cervical dilatation of <2 cm (n=10), 2–<4 cm (n=9), 4–6 cm (n=8), and >6 cm (n=9) were examined for nuclear fragmentation by the TUNEL assay, and for cell survival by the apoptosis-blocking bcl-2. Proliferation was marked by Ki-67, epithelial cells by cytokeratin and leukocytes by CD 45. For quantification of apoptotic and proliferating cells, eight random fields of each specimen stained for TUNEL or Ki-67 were blindly counted by two investigators. For statistical evaluation, 90% confidence intervals based on a Poisson distribution were used; groups with non-overlapping intervals were considered significantly different. Results: Apoptotic cells were found exclusively within the stromal compartment, while bcl-2 was expressed in epithelial cells and leukocytes. Proliferating cells were of stromal and epithelial origin. The number of apoptotic as well as proliferating cells ranged from 0 to 2 cells per high-power field (median number 0) in all groups. The confidence intervals were overlapping for all groups, showing no statistical difference between them. Conclusion: Apoptosis does not seem to play a decisive role in the process of cervical dilatation during parturition at term.

Evolutionary strategies of odontocete brain development

The development of the brain was studied in several species of toothed whales (harbour porpoise, spotted dolphin, narwhal, and sperm whale). As embryos, odontocetes show the general mammalian bauplan. The olfactory bulb, lacking in adult toothed whales, forms in embryos but then disappears in early fetal development. In contrast, the terminal nerve persists and shows a great increase in neuron number. Some components of the limbic system are reduced while others grow to become relatively large. The pyramidal tract is inconspicuous. The auditory system and the extrapyramidal system show rapid size increase. In the sperm whale, growth of the telencephalic hemispheres relative to the size of the brain as a whole (telencephalization) and expansion of the cortical areas (neocorticalization) are greater than in other mammals. Increases in the diameters of the cranial nerves seem to be correlated with their presumed functional roles in the postnatal animal.