Poly-(D,L-lactic acid) microspheres incorporating histological dyes for intra-pulmonary histopathological investigations.

Polylactic acid (PLA) microspheres incorporating fluorescein as a histological marker have been prepared and used as a model for the testing of inhaled PLA microspheres (2-5 microns) in the lung. PLA microspheres (20 mg) were delivered to rabbits in the form of a saline nebulization. The distribution pattern within the pulmonary system showed that the fluorescein-labelled microspheres were distributed about the four lobes in discrete groups.

Myelination of the corpus callosum. II. The effect of relief of hydrocephalus upon the processes of myelination.

A clinico-pathological study has been carried out on 32 brains of children with hydrocephalus in whom the hydrocephalus had been completely controlled by shunting. The cell and myelination activity of the corpus callosum in these children is within the normal range for children of the same age, which contrasts markedly with the findings in children in whom the hydrocephalus is in a progressive state.

The carotid body--a quantitative assessment in children.

The volume of the glomic tissue in the carotid bodies of 100 infants between the ages of 29 weeks gestation and 9 1/2 years has been determined by serial sections and point counting. There is a 10-fold variation in the size of the carotid body and the volume of glomic tissue at all ages studied. Forty of the infants died as unexpected deaths at home.

Staining of muscle tissue for quantitative studies and automated morphometry.

Seventy-six staining tests were carried out of paraffin sections of human and animal muscle to find a suitable staining method for quantitative morphometry of muscle fibers. The results were evaluated under the light microscope, on black and white photomicrographs and on an image analysing computer, the Quantimet 720.A brilliant scarlet-phosphotungstic acid-tartrazine method is described and recommended for automated morphometry after additional testing on 140 sections of developing human muscle using the Quantiment 720.