Morphological Characterization of Basally Located Uninucleate Trophoblast Cells as Precursors of Bovine Binucleate Trophoblast Giant Cells.

Binucleate trophoblast giant cells (TGCs) are one characteristic feature of the ruminant placenta. In cows, the frequency of TGCs remains constant for most of the duration of pregnancy. As TGCs are depleted by their fusion with uterine epithelial cells, they need to be constantly formed. It is still unclear whether they develop from stem cells within the trophectoderm or whether they can arise from any uninucleate trophoblast cell (UTC). Within the latter, generally accepted theory, a basally located uninucleate cell (BUC) without contact to the feto-maternal interface would represent a transient cell between a UTC and a TGC. So far, no evidence for the existence of such transient cells or for the presence of stem cells has been shown. The aim of the present study is to morphologically characterize the early stages of TGC development. Placentomal tissue of 6 pregnant cows from different gestational stages (gestational days 51-214) was examined for BUCs, UTCs, and TGCs either in serial sections (light and transmission electron microscopy, TEM, n = 3), in single sections (TEM, n = 2), or by serial block face-scanning electron microscopy (n = 1). These investigations revealed the occurrence of BUCs, as well as young TGCs showing contact with the basement membrane (BM), but without apical contact to the feto-maternal interface. The study morphologically defines these 2 cell types as early stages of TGC development and shows that binucleation of TGCs can precede detachment from the BM.

Ultrasonographic Examination of the Spinal Cord and Collection of Cerebrospinal Fluid from the Atlanto-Occipital Space in Cattle.

Ultrasonography is useful for the visualization of the spinal cord and associated structures and facilitates the safe collection of cerebrospinal fluid from the atlanto-occipital space in cattle. This technique is less stressful than the blind puncture technique because it does not require strong ventroflexion of the head. Furthermore, painful puncture of the spinal cord can largely be avoided when ultrasound guidance is used.

Ultrasonographic examination of the spinal cord and collection of cerebrospinal fluid from the atlanto-occipital space in cattle.

BACKGROUND: This study describes the ultrasonographic appearance of the atlanto-occipital space and ultrasound-guided collection of cerebrospinal fluid (CSF) in cattle. The atlanto-occipital space of 73 euthanized cattle (group A) and 14 live cattle with neurological disorders (group B) was examined in the sagittal and transverse planes using a 5.0-MHz convex transducer. Optimal ultrasonograms were frozen on the screen and various variables were measured in both planes using the electronic cursors. Puncture of the subarachnoid space was achieved using a spinal needle introduced in the median plane in a caudoventral direction while the spinal cord was viewed in longitudinal section. The examination of cerebrospinal fluid (CSF) was limited to gross evaluation and a red blood cell count. RESULTS: The spinal cord and the subarachnoid space were seen in the sagittal plane in all cattle. In group A, the mean distance between the skin and subarachnoid space was 38.6 mm, the mean depth of the subarachnoid space dorsal and ventral to the spinal cord was 8.9 mm and 8.4 mm, respectively, the mean diameter of the spinal cord was 9.9 mm and the mean diameter of the dural sac was 26.9 mm. These measurements were similar on transverse images. For collection of CSF from the subarachnoid space, the spinal cord was viewed in longitudinal section. All CSF samples from group A were colourless and clear and the median erythrocyte count was 2.5/µl. Ultrasonographic findings and results of CSF analysis were similar in group B. CONCLUSIONS: Ultrasonography is useful for the visualisation of the spinal cord and facilitates the safe collection of CSF from the atlanto-occipital space in cattle.