The Archived P5 Survival Series
This page links you to all the tritiated-thymidine injection groups that survived to postnatal day (P) 5. 11 to 14 different levels were chosen from one specimen in each injection group, beginning with the olfactory bulb as Level 1. The remaining Levels are from progressively more posterior parts of the brain. The last Level is from the medulla or cervical spinal cord. All of the slices are in the coronal plane only. There are 2 images shown for each Level, one of the brain in the head and another of the brain only. All images are presented without any labels to identify structures–we are working on adding that information at a later date.
With the exception of the hippocampus and cerebellum, P5 brain structures have a very similar appearance to the mature brain. Even the late developing olfactory bulb appears mature. Consequently, this survival group can substitute for the lack of a prenatally injected adult survival series in our archived library on this website. As I briefly stated in the Autoradiographic Brain Map Sets page, the P60 survival series that we used to construct neurogenetic timetables for various populations could not be archived because the stain has faded.
Methods: Several pregnant female rats were injected on 2 consecutive days with tritiated-thymidine beginning on E13+14, another on E14+15, and so on, until the last one was injected on E21+22. The females gave birth normally and on P5, all offspring were perfused through the heart with 10% neutral formalin. The head and body were cut transversely (coronally) into approximately 5 blocks: two head blocks (anterior and posterior), a neck block, and two or three trunk blocks. The blocks were stored in Bouin’s fixative for 24 hours, then transferred back to 10% neutral formalin with a chelating agent to decalcify bone so that we could study peripheral neurons. After decalcification, the blocks were embedded in paraffin. Serial 6µm coronal slices were placed on microscopic slides. The deparaffinized slices were coated with liquid Kodak NTB3 photographic emulsion in a humid darkroom. The slides were placed in light-tight boxes and stored in a refrigerated room for a 3-month exposure period. Then the slides were developed in Kodak D-19 and the tissue was post-stained with hematoxylin alone or with hematoxylin and eosin.
Links to each set of archived images–ALL IMAGES HAVE BEEN UPLOADED: